Cyclic diol-derived blocked mercaptofunctional silane compositions

ABSTRACT

Diol derived blocked mercaptofunctional silane compositions in which the silanes comprise cyclic and bridged alkoxy groups derived from hydrocarbon-based diols and processes for their preparation are provided. Also provided are rubber compositions comprising the cyclic diol-derived blocked mercaptofunctional silanes, processes for their preparation and articles of manufacture comprising the rubber compositions, in particular, automotive tires and components thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending U.S. patentapplication Ser. No. 10/922,426, filed Aug. 20, 2004, the entirecontents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to the cyclic diol-derivedblocked mercaptofunctional silane compositions, processes for theirpreparation, and rubber compositions comprising same.

2. Description of Related Art

A number of ether-based diol derivatives of sulfur silanes are known inthe art that suffer from a tendency to yield bridged structures in favorof cyclic structures exclusively or primarily, leading to highviscosities and gellation, which limits their usefulness in elastomermanufacture. These silanes and their use further suffer from the hazardsassociated with the use of ethers, which have a tendency to formperoxides spontaneously, thereby presenting a substantial flammabilityrisk and possibly interfering with the use of these silanes as couplingagents.

Also described in the prior art are blocked mercaptofunctional silanes,such as thiocarboxylate-functional silanes, processes for theirpreparation and their use in rubber compositions. A presentation on thesubject was also given at the 2002 International Tire Exposition andConference (ITEC) in Akron, Ohio. This art generally describesthiocarboxylate-functional silanes whose hydrolysable groups are derivedfrom simple monofunctional alcohols.

The prior art also describes processes for the preparation of cyclicalkoxysilanes by reacting difunctional and trifunctional alkoxysilanesor silazanes with glycols or other diols to form cyclic monomers. Thesesilanes however tend to self-polymerize to high viscosity polymericmaterials.

The prior art also describes the kinetics and mechanisms of substitutionreactions at the thiocarboxyl function in which the rate of alcoholysisof a thiol ester should be higher than the rate of thiolysis of anester. This means that the reaction equilibrium will favor thereplacement of the thiol group with the alcohol group.

The prior art does not address the use of cyclic diol-derived blockedmercapto functional silane compositions with reduced volatile organiccompound (“VOC”) emissions. Accordingly, there exists a need forimproved silanes.

BRIEF DESCRIPTION OF THE INVENTION

Silane compositions are provided herein comprising cyclic dialkoxyhaloalkyl silanes and cyclic dialkoxy thiocarboxylate silanecompositions. These silanes are derived from diols and release diolsduring use, as opposed to the ethanol released during the use of thethiocarboxylate silanes and/or polysulfide silanes used in the priorart. The diols are very resistant to volatilization owing to their lowvolatility, thereby resulting in a substantially reduced level of VOCemissions during use.

Accordingly, in a first embodiment of the present invention, a cyclicand bridging dialkoxy silane composition is provided comprising at leastone component selected from the group consisting of:

[[[(ROC(═O))_(p)-(G)_(j)]_(k)—Y—S]_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c)_(w))_(s)]_(n), and

[[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]_(a)-[Y—[S-G-SiX_(u)Z^(b)_(v)Z^(c) _(w)]_(b)]_(c)]_(n),

wherein

each occurrence of Y is independently selected from a polyvalent species(Q)_(z)A(=E), wherein the atom (A) attached to an unsaturated heteroatom(E) is attached to a sulfur, which in turn is linked via a group G to asilicon atom;

each occurrence of R is independently selected from the group consistingof hydrogen, straight, cyclic or branched alkyl that may or may notcontain unsaturation, alkenyl groups, aryl groups, and aralkyl groups,with each R, other than hydrogen, containing from 1 to about 18 carbonatoms;

each occurrence of G is independently selected from the group consistingof monovalent and polyvalent groups derived by substitution of alkyl,alkenyl, aryl, or aralkyl wherein G can comprise from 1 to about 30carbon atoms, with the proviso that if G is univalent, G can behydrogen;

each occurrence of Z^(b), which forms a bridging structure between twosilicon atoms, is independently selected from the group consisting of(—O—)_(0.5) and [—O(R⁴CR⁵)_(f)O—]_(0.5), wherein each occurrence of R⁴and R⁵ is independently R;

each occurrence of Z^(c), which forms a cyclic structure with a siliconatom, is independently given by —O(R⁴CR⁵)_(f)O—; wherein each occurrenceof R⁴ and R⁵ is independently R;

each occurrence of X is independently selected from the group consistingof —Cl, —Br, R¹O—, R¹O(R⁴CR⁵)_(f)O—, R¹C(═O)O—, R¹R²C═NO—, R¹R²NO—,R¹R²N—, —R¹, and —(OSiR¹R²)_(t)(OSiR¹R²R³), wherein each occurrence ofR¹, R², R³R⁴ and R⁵ is independently R;

each occurrence of Q is independently selected from oxygen, sulfur or(—NR—);

each occurrence of A is independently selected from carbon, sulfur,phosphorus or sulfonyl;

each occurrence of E is independently selected from oxygen, sulfur or(—NR—);

each occurrence of the subscripts, u, n, v, w, f, p, r, z, q, a, b, j,p, c, t, s, and k, is independently given by u is 0 to about 3; n is 1to about 100, with the proviso that when n is greater than 1, v isgreater than 0 and all the valences for Z^(b) have a silicon atom bondedto them; v is 0 to about 3; w is 0 to about 1; u+v+2w is 3; f is 1 toabout 15; p is 0 to about 5; r is 1 to about 3; z is 0 to about 2; q is0 to about 6; a is 0 to about 7; b is 1 to about 3; j is 0 to about 1,but it may be 0 only if p is 1, c is 1 to about 6; t is 0 to about 50; sis 1 to about 3; and k is 1 to about 2, with the provisos that (I) if Ais carbon, sulfur, or sulfonyl, then (i) a+b is 2 and (ii) k is 1; (II)if A is phosphorus, then a+b is 3 unless both (i) c is greater than 1and (ii) b is 1, in which case a is c+1; and (III) if A is phosphorus,then k is 2; and wherein that each of the above structures comprise atleast one hydrolysable group, Z^(b) or Z^(c), that is a difunctionalalkoxy group.

In a second embodiment of the present invention, a process for thepreparation of a cyclic and bridging dialkoxy blocked mercaptofunctionalsilane composition is provided comprising reacting an aqueous solutionof a salt of at least one thiocarboxylate acid with at least one cyclicand bridging dialkoxy haloalkyl silane and, optionally, at least onehaloalkyl silane, in the presence or absence of at least one phasetransfer catalyst. In one embodiment, the cyclic and bridging dialkoxyhaloalkyl silanes and haloalkyl silanes are, respectively, of thestructures:

L_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c) _(w))_(s), and

L_(r)-G-(SiX₃)_(s)

and the structures for the thiocarboxylate salts are:

G(-Y¹-SM)_(d)

[(ROC(═O))_(p)-(G)_(j)]-Y¹-SM or

[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]-Y¹-SM].

wherein

each occurrence of M is independently selected from alkali metal;ammonium; or mono-, di-, or tri-substituted ammonium;

each occurrence of Y¹ is independently carbonyl; and d is 1 to about 6and R, L, G, X, Z^(b), Z^(c), j, p, q, u, v, w, r, and s have theaforestated meanings.

In accordance with a third embodiment of the present invention, a rubbercomposition is provided comprising (a) a rubber component; (b) a fillerand (c) at least one cyclic and bridging dialkoxy blockedmercaptofunctional silane composition comprising at least one componentselected from the group consisting of

[[[(ROC(═O))_(p)-(G)_(j)]_(k)-Y—S]_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c)_(w))_(s)]_(n), and

[[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]_(a)-[Y—[S-G-SiX_(u)Z^(b)_(v)Z^(c) _(w)]_(b)]_(c)]_(n),

wherein R, G, Y, X, Z^(b), Z^(c), u, v, w, f, p, r, z, q, a, b, j, c, t,s, k and n have the aforestated meanings, and wherein that each of theabove structures comprise at least one hydrolysable group, Z^(b) orZ^(c), that is a difunctional alkoxy group.

In accordance with a fourth embodiment of the present invention, aprocess for preparing a rubber composition is provided comprising addingto a rubber composition reaction-forming mixture an effective amount ofat least one cyclic and bridging dialkoxy blocked mercaptofunctionalsilane composition comprising at least one component selected from thegroup consisting of:

[[[(ROC(═O))_(p)-(G)_(j)]_(k)-Y—S]_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c)_(w))_(s)]_(n), and

[[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]_(a)-[Y—[S-G-SiX_(u)Z^(b)_(v)Z^(c) _(w)]_(b)]_(c)]_(n),

wherein R, G, Y, X, Z^(b), Z^(c), u, v, w, f, p, r, z, q, a, b, j, c, t,s, k and n have the aforestated meanings, and wherein that each of theabove structures comprise at least one hydrolysable group, Z^(b) orZ^(c), that is a difunctional alkoxy group.

In accordance with a fifth embodiment, the present invention, an articleof manufacture, in particular tires and tire treads, is providedcomprising at least one cyclic and bridging dialkoxy silane compositioncomprising at least one component selected from the group consisting of:

[[[(ROC(═O))_(p)-(G)_(j)]_(k)-Y—S]_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c)_(w))_(s)]_(n), and

[[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]_(a)-[Y—[S-G-SiX_(u)Z^(b)_(v)Z^(c) _(w)]_(b)]_(c)]_(n),

wherein R, G, Y, X, Z^(b), Z^(c), u, v, w, f, p, r, z, q, a, b, j, c, t,s, k and n have the aforestated meanings, and wherein that each of theabove structures comprise at least one hydrolysable group, Z^(b) orZ^(c), that is a difunctional alkoxy group.

DETAILED DESCRIPTION OF THE INVENTION Cyclic and Bridging DialkoxyHaloalkyl Silane and Cyclic and Bridging Dialkoxy BlockedMercaptofunctional Silane Compositions: Silane Structures

In one embodiment of the present invention, cyclic and bridging dialkoxyblocked mercaptofunctional silanes are provided as represented by thegeneral formulae (1-2):

[[[(ROC(═O))_(p)-(G)_(j)]_(k)-Y—S]_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c)_(w))_(s)]_(n)  (Formula 1)

[[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]_(a)-[Y—[S-G-SiX_(u)Z^(b)_(v)Z^(c) _(w)]_(b)]_(c)]_(n)  (Formula 2)

In another embodiment of the present invention, cyclic and bridgingdialkoxy haloalkyl silane compositions can comprise single components ormixtures of components whose individual chemical structures can berepresented by Formula 3:

L_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c) _(w))_(s)  (Formula 3)

In Formulae 1, 2 and 3:

each occurrence of Y is independently a polyvalent species (Q)_(z)A(=E),wherein the atom (A) attached to the unsaturated heteroatom (E) isattached to the sulfur, which in turn is linked via a group G to thesilicon atom including, by way of example, —C(═NR)—; —SC(═NR)—;—SC(═O)—; (—NR)C(═O)—; (—NR)C(═S)—; —OC(═O)—; —OC(═S)—; —C(═O)—;—SC(═S)—: —C(═S)—; —S(═O)—; —S(═O)₂—; —OS(═O)₂—; (—NR)S(═O)₂—; —SS(═O)—;—OS(═O)—; (—NR)S(═O)—; —SS(═O)₂—; (—S)₂P(═O)—; —(—S)P(═O)—; —P(═O)(—)₂;(—S)₂P(═S)—; —(—S)P(═S)—; —P(═S)(—)₂; (—NR)₂P(═O)—; (—NR)(—S)P(═O)—;(—O)(—NR)P(═O)—; (—O)(—S)P(═O)—; (—O)₂P(═O)—; —(—O)P(═O)—; —(—NR)P(═O)—;(—NR)₂P(═S)—; (—NR)(—S)P(═S)—; (—O)(—NR)P(═S)—; (—O)(—S)P(═S)—;(—O)₂P(═S)—; —(—O)P(—S)—; and —(—NR)P(═S)—;

each occurrence of R is independently selected from hydrogen, straight,cyclic or branched alkyl that may or may not be unsaturated, alkenylgroups, aryl groups, and aralkyl groups, with each R, other thanhydrogen, having from 1 to about 18 carbon atoms such as methyl, ethyl,propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octenyl, cyclohexyl,phenyl, benzyl, and the like;

each occurrence of G is independently selected from a monovalent orpolyvalent group derived by substitution of alkyl, alkenyl, aryl oraralkyl wherein G can comprise from 1 to about 30 carbon atoms, with theproviso that if G is univalent (i.e., if p=0), G can be a hydrogen atom;

each occurrence of X is independently selected from the group consistingof —Cl, —Br, R¹O—, R¹O(R⁴CR⁵)_(f)O—, R¹C(═O)O—, R¹R²C═NO—, R¹R²NO—,R¹R²N—, —R¹, and —(OSiR¹R²)_(t)(OSiR¹R²R³), wherein each occurrence ofR¹, R² and R³ is independently R;

each occurrence of Z^(b), which forms a bridging structure between twosilicon atoms, is independently selected from group consisting of(—O—)_(0.5), and [—O(R⁴CR⁵)_(f)O—]_(0.5), wherein each occurrence of R⁴and R⁵ is independently R;

each occurrence of Z^(c), which forms a cyclic structure with a siliconatom, is independently given by —O(R⁴CR⁵)_(f)O— wherein each occurrenceof R⁴ and R⁵ is independently R;

each occurrence of Q is independently oxygen, sulfur or (—NR—);

each occurrence of A is independently carbon, sulfur, phosphorus orsulfonyl;

each occurrence of E is independently oxygen, sulfur or (—NR—);

each occurrence of L is independently a halogen atom (i.e., F, Cl, Br,or I), sulfonate group, sulfinate group, or carboxylate group;

each occurrence of the subscripts, u, n, v, w, f, p, r, z, q, a, b, j,p, c, t, s, and k, is independently given by u is 0 to about 3; n is 1to about 100 and all subranges therebetween, with the proviso that whenn is greater than 1, v is greater than 0 and all the valences for Z^(b)have a silicon atom bonded to them; v is 0 to about 3; w is 0 to about1; u+v+2w is about 3; f is 1 to about 15; p is 0 to about 5; r is 1 toabout 3; z is 0 to about 2; q is 0 to about 6; a is 0 to about 7; b is 1to about 3; j is 0 to about 1, but it may be 0 only if p is 1, c is 1 toabout 6; t is 0 to about 50; s is 1 to about 3; and k is 1 to about 2,with the provisos that (I) if A is carbon, sulfur or sulfonyl, then (i)a+b is 2 and (ii) k is 1; (II) if A is phosphorus, then a+b is 3 unlessboth (i) c is greater than 1 and (ii) b is 1, in which case a is c+1;and (III) if A is phosphorus, then k is 2; and wherein that thestructures described by Formulae 1, 2 and 3 comprise at least onehydrolysable group, Z^(b) or Z^(c), that is a difunctional alkoxy group.

As used herein, the terms “diol” and “difunctional alcohol” refer to anystructure given by Formula 4, set forth hereinbelow, wherein f, R⁴ andR⁵ have the aforestated meanings. These structures representhydrocarbons in which two hydrogen atoms are replaced with OH inaccordance with the structures drawn in Formula 4.

The terms “dialkoxy” and “difunctional alkoxy” as used herein refer tohydrocarbon-based diols in which the two OH hydrogen atoms have beenremoved to give divalent radicals, and whose structures are given byFormula 5, set forth hereinbelow, wherein f, R⁴ and R⁵ have theaforestated meanings.

The term “cyclic dialkoxy” as used herein refers to a silane or group inwhich cyclization is about silicon, by two oxygen atoms each attached toa common divalent hydrocarbon group, such as is commonly found in diols.Cyclic dialkoxy groups herein are represented by Z^(c). The structure ofZ^(c) is advantageous in the formation of the cyclic structure. R⁴ andR⁵ groups that are more sterically hindered than hydrogen promote theformation of cyclic structures. The formation of cyclic structures isalso promoted when the value of f in Formula 5 is 2 or 3.

The term “bridging dialkoxy” as used herein refers to a silane or groupin which two different silicon atoms are each bound to one oxygen atom,which in turn is bound to a common divalent hydrocarbon group, such asis commonly found in diols. Bridging dialkoxy groups herein arerepresented by substituent Z^(b).

The term “hydrocarbon based diols” as used herein refers to diols thatcomprise two OH groups on a hydrocarbon structure. Absent from thehydrocarbon based diols are heteroatoms (other than, of course, the twoOH groups), in particular ether groups, which are avoided because ofproblems associated with their tendency to form peroxides spontaneously,which lead to flammability hazards and free radical formation.

Formulae 4 and 5 can be represented as follows:

HO(R⁴CR⁵)_(f)OH  (Formula 4)

—O(R⁴CR⁵)_(f)O—  (Formula 5)

The structure given by Formula 4 will herein be referred to as theappropriate diol (in a few specific cases, glycol is the more commonlyused term), prefixed by the particular hydrocarbon group associated withthe two OH groups. Examples include, but are not limited to,neopentylglycol, 1,3-butanediol, and 2-methyl-2,4-pentanediol.

The groups whose structures are given by Formula 5 will herein bereferred to as the appropriate dialkoxy, prefixed by the particularhydrocarbon group associated with the two OH groups. Diols, such as, forexample, neopentylglycol, 1,3-butanediol and 2-methyl-2,4-pentanediol,correspond herein to the dialkoxy groups, neopentylglycoxy,1,3-butanedialkoxy, and 2-methyl-2,4-pentanedialkoxy, respectively.

Cyclic and bridging dialkoxy blocked mercaptofunctional silanes herein,in which the diol from which the silane is derived is commonly referredto as a glycol, are named as the corresponding glycoxysilane. Cyclicdialkoxy silanes herein, in which the diol from which the silane isderived is commonly referred to as a diol, are named as thecorresponding dialkoxysilane.

As used herein for Z^(b), the notations, (—O—)_(0.5) and[—O(R⁴CR⁵)_(f)O—]_(0.5), refer to one-half of a siloxane bond, andone-half of a bridging dialkoxy group, respectively. These notations areused in conjunction with a silicon atom and they are taken herein tomean one-half of an oxygen atom, namely, the half bound to theparticular silicon atom, or to one-half of a dialkoxy group, namely, thehalf bound to the particular silicon atom, respectively. It isunderstood that the other half of the oxygen atom or dialkoxy group andits bond to silicon occurs somewhere else in the overall molecularstructure being described. Thus, the (—O—)_(0.5) siloxane groups and the[—O(R⁴CR⁵)_(f)O—]_(0.5) dialkoxy groups mediate the chemical bonds thathold two separate silicon atoms together, whether these two siliconatoms occur intermolecularly or intramolecularly. In the case of[—O(R⁴CR⁵)_(f)O—]_(0.5), if the hydrocarbon group, (R⁴CR⁵)_(f), isunsymmetrical, either end of [—O(R⁴CR⁵)_(f)O—]_(0.5) may be bound toeither of the two silicon atoms required to complete the structuresgiven in Formulae 1, 2, and 3.

The term “alkyl” as used herein includes straight, branched and cyclicalkyl groups. The term “alkenyl” as used herein includes any straight,branched, or cyclic alkenyl group comprising one or more carbon-carbondouble bonds, where the point of substitution can be either at acarbon-carbon double bond or elsewhere in the group. The term “alkynyl”as used herein includes any straight, branched, or cyclic alkynyl groupcomprising one or more carbon-carbon triple bonds and, optionally, oneor more carbon-carbon double bonds as well, where the point ofsubstitution can be either at a carbon-carbon triple bond, acarbon-carbon double bond, or elsewhere in the group. Examples of alkylsinclude, but are not limited to, methyl, ethyl, propyl, and isobutyl.Examples of alkenyls include, but are not limited to, vinyl, propenyl,allyl, methallyl, ethylidenyl norbornane, ethylidene norbornyl,ethylidenyl norbornene, and ethylidene norbornenyl. Examples of alkynylsinclude, but are not limited to, acetylenyl, propargyl, andmethylacetylenyl.

The term “aryl” as used herein includes any aromatic hydrocarbon fromwhich one hydrogen atom has been removed useful aralkyl includes, but isnot limited to, any of the aforementioned alkyl groups in which one ormore hydrogen atoms have been substituted by the same number of likeand/or different aryl (as defined herein) substituents; and “arenyl”includes any of the aforementioned aryl groups in which one or morehydrogen atoms have been substituted by the same number of like and/ordifferent alkyl (as defined herein) substituents. Examples of arylsinclude, but are not limited to, phenyl and naphthalenyl. Examples ofaralkyls include, but are not limited to, benzyl and phenethyl. Examplesof arenyls include, but are not limited to, tolyl and xylyl.

The terms “cyclic alkyl”, “cyclic alkenyl”, and “cyclic alkynyl” as usedherein also include bicyclic, tricyclic, and higher cyclic structures,as well as the aforementioned cyclic structures further substituted withalkyl, alkenyl, and/or alkynyl groups. Representative examples include,but are not limited to, norbornyl, norbornenyl, ethylnorbornyl,ethylnorbornenyl, ethylcyclohexyl, ethylcyclohexenyl,cyclohexylcyclohexyl, and cyclododecatrienyl.

Representative examples of the functional groups (—YS—) present in thesilanes of the present invention include, but are not limited to,thiocarboxylate ester, —C(═O)—S— (any silane with this functional groupis a “thiocarboxylate ester silane”); dithiocarboxylate, —C(═S)—S— (anysilane with this functional group is a “dithiocarboxylate estersilane”): thiocarbonate ester, —O—C(═O)—S— (any silane with thisfunctional group is a “thiocarbonate ester silane”); dithiocarbonateester, —S—C(═O)—S— and —O—C(═S)—S— (any silane with this functionalgroup is a “dithiocarbonate ester silane”); trithiocarbonate ester,—S—C(═S)—S— (any silane with this functional group is a“trithiocarbonate ester silane”); dithiocarbamate ester, N—C(═S)—S-(anysilane with this functional group is a “dithiocarbamate ester silane”);thiosulfonate ester, —S(═O)₂—S— (any silane with this functional groupis a “thiosulfonate ester silane”); thiosulfate ester, —O—S(═O)₂—S— (anysilane with this functional group is a “thiosulfate ester silane”);thiosulfamate ester, (—N—)S(═O)₂—S— (any silane with this functionalgroup is a “thiosulfamate ester silane”); thiosulfinate ester,C—S(═O)—S— (any silane with this functional group is a “thiosulfinateester silane”): thiosulfite ester, —O—S(═O)—S— (any silane with thisfunctional group is a “thiosulfite ester silane”): thiosulfimate ester,N—S(═O)—S-(any silane with this functional group is a “thiosulfimateester silane”); thiophosphate ester. P(═O)(O—)₂(S—) (any silane withthis functional group is a “thiophosphate ester silane”);dithiophosphate ester. P(═O)(O—)(S—)₂ or P(═S)(O—)₂(S—) (any silane withthis functional group is a “dithiophosphate ester silane”):trithiophosphate ester, P(═O)(S—)₃ or P(═S)(O—)(S—)₂ (any silane withthis functional group is a “trithiophosphate ester silane”);tetrathiophosphate ester P(═S)(S—)₃ (any silane with this functionalgroup is a “tetrathiophosphate ester silane”); thiophosphamate ester,—P(═O)(—N—)(S—) (any silane with this functional group is a“thiophosphamate ester silane”); dithiophosphamate ester,—P(═S)(—N—)(S—) (any silane with this functional group is a“dithiophosphamate ester silane”); thiophosphoramidate ester,(—N—)P(═O)(O—)(S—) (any silane with this functional group is a“thiophosphoramidate ester silane”); dithiophosphoramidate ester,(—N—)P(═O)(S—)₂ or (—N—)P(═S)(O—)(S—) (any silane with this functionalgroup is a “dithiophosphoramidate ester silane”); trithiophosphoramidateester, silane”).

In one embodiment, the functional group (—YS—) can be —C(═O)—S—;—SC(═O)S—; —SC(═S)—; —OC(═O)—; —SC(═O)—; —S(═O)—; —OS(═O)—; —(—S)P(═O)—;—P(═O)(—)₂ and the like.

In one embodiment of the present invention, n is an integer between 1and about 10 and all subranges therebetween.

In one embodiment of the present invention, the silane can be wherein Yis —C(═O)— and G has a primary carbon attached to the carbonyl and is aC₁ to about C₁₈ alkyl. In yet another embodiment, G can be a C₃ to aboutC₁₂ alkyl. In yet another embodiment, G can be a C₆ to about C₁₀ alkyl.

In still another embodiment of the present invention, the silane can berepresented by the following structure [X_(u)Z^(b) _(v)Z^(c)_(w)SiGSC(═O)GC(═O)SGSiX_(u)Z^(b) _(v)Z^(c) _(w)]_(n) wherein G is adivalent hydrocarbon radical.

Representative examples of G include, but are not limited to,CH₃(CH₂)_(g)— wherein g is 1 to about 29 and all subranges therebetween;diethylene cyclohexane; 1,2,4-triethylene cyclohexane; diethylenebenzene; phenylene; —(CH₂)_(g)— wherein g is 1 to about 29, whichrepresent the terminal straight-chain alkyls further substitutedterminally at the other end, such as —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, and—CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—, and their beta-substituted analogs, such as,for example, —CH₂(CH₂)_(m)CH(CH₃)—, where m is 0 to about 17;—CH₂CH₂C(CH₃)₂CH₂—; the structure derivable from methallyl chloride,—CH₂CH(CH₃)CH₂—; any of the structures derivable from divinylbenzene,such as, for example, —CH₂CH₂(C₆H₄)CH₂CH₂— and —CH₂CH₂(C₆H₄)CH(CH₃)—,where the notation C₆H₄ denotes a disubstituted benzene ring; any of thestructures derivable from dipropenylbenzene, such as—CH₂CH(CH₃)(C₆H₄)CH(CH₃)CH₂—, where the notation C₆H₄ denotes adisubstituted benzene ring; any of the structures derivable frombutadiene, such as —CH₂CH₂CH₂CH₂—, —CH₂CH₂CH(CH₃)—, and —CH₂CH(CH₂CH₃)—;any of the structures derivable from piperylene, such as—CH₂CH₂CH₂CH(CH₃)—, —CH₂CH₂CH(CH₂CH₃)—, and —CH₂CH(CH₂CH₂CH₃)—; any ofthe structures derivable from isoprene, such as —CH₂CH(CH₃)CH₂CH₂—,—CH₂CH(CH₃)CH(CH₃)—, —CH₂C(CH₃)(CH₂CH₃)—, CH₂CH₂CH(CH₃)CH₂—,—CH₂CH₂C(CH₃)₂— and —CH₂CH[CH(CH₃)₂]—; any of the isomers of—CH₂CH₂-norbornyl-, —CH₂CH₂-cyclohexyl-; any of the diradicalsobtainable from norbornane, cyclohexane, cyclopentane,tetrahydrodicyclopentadiene, or cyclododecene by loss of two hydrogenatoms; the structures derivable from limonene, —CH₂CH(4-CH₃-1-C₆H₉—)CH₃,where the notation C₆H₉ denotes isomers of the trisubstitutedcyclohexane ring lacking substitution in the 2 position; any of themonovinyl-comprising structures derivable from trivinylcyclohexane, suchas —CH₂CH₂(vinylC₆H₉)CH₂CH₂— and —CH₂CH₂(vinylC₆H₉)CH(CH₃)—, where thenotation C₆H₉ denotes any isomer of the trisubstituted cyclohexane ring;any of the monounsaturated structures derivable from myrcene comprisinga trisubstituted C═C, such as —CH₂CH[CH₂CH₂CH═C(CH₃)₂]CH₂CH₂—,—CH₂CH[CH₂CH₂CH═C(CH₃)₂]CH(CH₃)—, —CH₂C[CH₂CH₂CH═C(CH₃)₂](CH₂CH₃)—,—CH₂CH₂CH[CH₂CH₂CH═C(CH₃)₂]CH₂—, —CH₂CH₂(C—)(CH₃)[CH₂CH₂CH═C(CH₃)₂], and—CH₂CH[CH(CH₃)[CH₂CH₂CH═C(CH₃)₂]]—; and any of the monounsaturatedstructures derivable from myrcene lacking a trisubstituted C═C, such as—CH₂CH(CH═CH₂)CH₂CH₂CH₂C(CH₃)₂—, —CH₂CH(CH═CH₂)CH₂CH₂CH[CH(CH₃)₂]—,—CH₂C(═CH—CH₃)CH₂CH₂CH₂C(CH₃)₂—, —CH₂C(═CH—CH₃)CH₂CH₂CH[CH(CH₃)₂]—,—CH₂CH₂C(═CH₂)CH₂CH₂CH₂C(CH₃)₂—, —CH₂CH₂C(═CH₂)CH₂CH₂CH[CH(CH₃)₂]—,—CH₂CH═C(CH₃)₂CH₂CH₂CH₂C(CH₃)₂—, and —CH₂CH═C(CH₃)₂CH₂CH₂CH[CH(CH₃)₂].

In one embodiment, the structures for G are those in which the sum ofthe carbon atoms within the G groups within the molecule are from 3 toabout 18 and all subranges therebetween. In another embodiment, thestructures for G are those in which the sum of the carbon atoms withinthe G groups within the molecule are from 6 to about 14 and allsubranges therebetween. This amount of carbons in the blockedmercaptosilane facilitates the dispersion of the inorganic filler intothe organic polymers, thereby improving the balance of properties in thecured filled rubber composition. In another embodiment, G can be—CH₂CH₂CH₂— and CH₃CH₂CH₂CH₂CH₂CH₂CH₂—.

Representative examples of R, R⁴ and R⁵ groups include R, but are notlimited to hydrogen, branched and straight-chain alkyls of 1 to 18carbon atoms or more, such as methyl, ethyl, propyl, isopropyl, octenyl,cyclohexyl, and butyl; phenyl; benzyl; tolyl; and allyl. In oneembodiment, the R groups are C₁ to C₄ alkyls, and hydrogen. In anotherembodiment, the R⁴ and R⁵ groups are independently hydrogen, methyl,ethyl, and propyl.

Specific examples of X are methoxy, ethoxy, isobutoxy, propoxy,isopropoxy, acetoxy and oximato. X may also be a monovalent alkyl group,such as methyl and ethyl. In one embodiment, X is methoxy, acetoxy orethoxy.

Specific examples of Z^(b) and Z^(c) are the divalent alkoxy groupsderived from diols such as, for example, ethylene glycol, propyleneglycol, neopentyl glycol, 1,3-propanediol, 2-methyl-1,3-propanediol,1,3-butanediol, 2-methyl-2,4-pentanediol, 1,4-butanediol, cyclohexanedimethanol, and pinacol. In one embodiment, the divalent alkoxy groupsare derived from ethylene glycol, propylene glycol, neopentyl glycol,1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol or2-methyl-2,4-pentanediol. In another embodiment, the divalent alkoxygroups are derived from 1,3-propanediol, 2-methyl-1,3-propanediol,1,3-butanediol or 2-methyl-2,4-pentanediol.

The cyclic dialkoxy content of the silanes herein must be keptsufficiently high relative to the total dialkoxy content present toprevent excessive crosslinking, which could lead to gellation. In oneembodiment, v and w in Formulae 1, 2, and 3 are such that the ratio,v/w, is between 0 and about 1. In another embodiment, the ratio, v/w, isbetween 0 and about 0.1. In yet another embodiment, the ratio, v/w, iszero.

In one embodiment, v and w in Formulae 1, 2, and 3 are such that theratio, v/w, is between 0 and about 1; p is 0 to 2; X is RO— or RC(═O)O—;Z^(b) and Z^(c) are the divalent alkoxy groups derived from1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, and/or2-methyl-2,4-pentanediol; R is C₁ to C₄ alkyl or hydrogen; and G is astraight chain alkyl of 3 to about 18 carbon atoms. In anotherembodiment, the ratio, v/w, is between 0 and about 0.1; X is ethoxy;Z^(b) and Z^(c) are the divalent alkoxy groups derived from1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, and/or2-methyl-2,4-pentanediol; and G is a C₃ to about C₁₂ straight-chainalkyl derivative.

In another embodiment of the present invention, when in the silane p is0, s, r, j and k each is 1, n is 1 to 3, X is —OC₂H₅, Y is —C(═O)—, G is—(CH₂)₃— or —(CH₂)₆CH₃, then either w is 0 or at least one occurrence ofZ^(b) is (—O—)_(0.5).

Representative examples of the cyclic and bridging dialkoxy blockedmercaptofunctional silanes of the present invention include, but are notlimited to, 2-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-ethylthioacetate; 2-(2-methyl-2,4-pentanedialkoxymethoxysilyl)-1-ethylthioacetate; 2-(2-methyl-2,4-pentanedialkoxy methylsilyl)-1-ethylthioacetate; 3-(2-methyl-2,4-pentanedialkoxymethoxysilyl)-1-propylthioacetate; 2-methyl-2,4-pentanedialkoxyethoxysilylmethyl thioacetate;2-methyl-2,4-pentanedialkoxyisopropoxysilylmethyl thioacetate;neopentylglycoxypropoxysilylmethyl thioacetate;propyleneglycoxymethylsilylmethyl thioacetate;neopentylglycoxyethylsilylmethyl thioacetate;2-(neopentylglycoxyisopropoxysilyl)-1-ethyl thioacetate;2-(neopentylglycoxy methylsilyl)-1-ethyl thioacetate;2-(1,3-butanedialkoxymethylsilyl)-1-ethyl thioacetate;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl thioacetate;3-(1,3-butanedialkoxyisopropoxysilyl)-4-butyl thioacetate:3-(1,3-butanedialkoxyethylsilyl)-1-propyl thioacetate;3-(1,3-butanedialkoxymethylsilyl)-1-propyl thioacetate;6-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-hexyl thioacetate;1-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-5-hexyl thioacetate;8-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-octyl thioacetate;10-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-decyl thioacetate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiododecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-methylheptanoate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl)dithioadipate;6-(1,3-butanedialkoxyethoxysilyl)-1-hexyl thioacetate;1-(1,3-butanedialkoxyethoxysilyl)-5-hexyl thioacetate;8-(1,3-butanedialkoxyethoxysilyl)-1-octyl thioacetate;10-(1,3-butanedialkoxyethoxysilyl)-1-decyl thioacetate;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(1,3-butanedialkoxypropoxysilyl)-1-propyl thiododecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-methylheptanoate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl)dithioadipate;tris-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl)trithiophosphate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyl)methyldithiophosphonate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyl)ethyldithiophosphonate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyldimethylthiophosphinate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyldiethylthiophosphinate;tris-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyl)tetrathiophosphate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyl)methyltrithiophosphonate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyl)ethyltrithiophosphonate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyldimethyldithiophosphinate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propyldiethyldithiophosphinate;tris-(3-(2-methyl-2,4-pentanedialkoxy-methyl-silyl-1-propyl)trithiophosphate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propylmethylthiosulphate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propylmethanethiosuiphonate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propylethanethiosulphonate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl-1-propylbenzenethiosulphonate;and the like.

In another embodiment, cyclic and bridging dialkoxy blockedmercaptofunctional silanes include, but are not limited to,3-(2-methyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-[2-methyl-1,3-propanedialkoxy(2-methyl-3-hydroxypropoxy)silyl]-1-propylthiooctanoate; 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthiodecanoate; 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthiododecanoate; 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthiotetradecanoate; 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-methylheptanoate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl) dithioadipateand the like.

In yet another embodiment, cyclic and bridging dialkoxy blockedmercaptofunctional silanes include, but are not limited to,3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiodecanoate;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl) dithioadipateand the like.

In one embodiment, the majority of the cyclic and bridging dialkoxyblocked mercaptofunctional silanes are cyclic and bridging dialkoxyanalogs to 3-octanoylthio-1-propyltriethoxysilane with, in some cases,minor variations of the carboxyl group.

Representative examples of the cyclic and bridging dialkoxy haloalkylsilanes of the present invention include, but are not limited, to2-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride;2-(2-methyl-2,4-pentanedialkoxyisopropoxysilyl)-1-propyl chloride;2-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl chloride;2-(2-methyl-2,4-pentanedialkoxyphenylsilyl)-1-propyl chloride;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl chloride;3-(1,3-butanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,3-propanedialkoxyethoxysilyl)-1-propyl chloride;3-(1,3-propanedialkoxyisopropoxysilyl)-1-propyl chloride:3-(1,2-propanedialkoxyethoxysilyl)-1-propyl chloride and3-(1,2-propanedialkoxyisopropoxysilyl)-1-propyl chloride, both derivablefrom propylene glycol; 3-(1,2-ethanedialkoxyethoxysilyl)-1-propylchloride and 3-(1,2-ethanedialkoxyisopropoxysilyl)-1-propyl chloride,both derivable from ethylene glycol; 3-(neopentylglycoxyethoxysilyl)-1-propyl chloride and 3-(neopentylglycoxyisopropoxysilyl)-1-propyl chloride, both derivable from neopentylglycol; 3-(2,3-dimethyl-2,3-butanedialkoxyethoxysilyl)-1-propyl chlorideand 3-(2,3-dimethyl-2,3-butanedialkoxyisopropoxysilyl)-1-propylchloride, both derivable from pinacol;3-(2,2-diethyl-1,3-propanedialkoxyethoxysilyl)-1-propyl chloride;3-(2,2-diethyl-1,3-propanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyethoxysilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,3-butanedialkoxymethylsilyl)-1-propyl chloride;3-(1,3-propanedialkoxymethylsilyl)-1-propyl chloride;3-(1,3-propanedialkoxyphenylsilyl)-1-propyl chloride;3-(1,2-propanedialkoxymethylsilyl)-1-propyl chloride and3-(1,2-propanedialkoxyphenylsilyl)-1-propyl chloride, both derivablefrom propylene glycol; 3-(1,2-ethanedialkoxymethylsilyl)-1-propylchloride and 3-(1,2-ethanedialkoxyphenylsilyl)-1-propyl chloride, bothderivable from ethylene glycol; 3-(neopentylglycoxymethylsilyl)-1-propyl chloride and 3-(neopentylglycoxyphenylsilyl)-1-propyl chloride, both derivable from neopentylglycol; 3-(2,3-dimethyl-2,3-butanedialkoxymethylsilyl)-1-propyl chlorideand 3-(2,3-dimethyl-2,3-butanedialkoxyphenylsilyl)-1-propyl chloride,both derivable from pinacol;3-(2,2-diethyl-1,3-propanedialkoxymethylsilyl)-1-propyl chloride;3-(2,2-diethyl-1,3-propanedialkoxyphenylsilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyethylsilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyphenylsilyl)-1-propyl chloride;2-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-ethyl chloride;2-(2-methyl-2,4-pentanedialkoxymethoxysilyl)-1-ethyl bromide;2-(2-methyl-2,4-pentanedialkoxy methylsilyl)-1-ethyl toluenesulfonate;2-methyl-2,4-pentanedialkoxyethoxysilylmethyl chloride;2-methyl-2,4-pentanedialkoxyisopropoxysilylmethyl bromide;neopentylglycoxypropoxysilylmethyl chloride;propyleneglycoxymethylsilylmethyl bromide;neopentylglycoxyethylsilylmethyl sulfinate;2-(neopentylglycoxyisopropoxysilyl)-1-ethyl chloride;2-(neopentylglycoxy methylsilyl)-1-ethyl bromide;2-(1,3-butanedialkoxymethylsilyl)-1-ethyl chloride;3-(1,3-butanedialkoxyisopropoxysilyl)-4-butyl bromide;3-(1,3-butanedialkoxyethylsilyl)-1-propyl bromide;3-(1,3-butanedialkoxymethylsilyl)-1-propyl benzenesulfonate;6-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-hexyl chloride;1-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-5-hexyl chloride;8-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-octyl chloride;10-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-decyl chloride;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl methanesulfonate;3-(2-methyl-2,4-pentanedialkoxypropoxysilyl)-1-propyl chloride;3-(2-methyl-2,4-pentanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(2-methyl-2,4-pentanedialkoxybutoxysilyl)-1-propyl bromide;3-(2-methyl-2,4-pentanedialkoxyisopropoxysilyl)-1-propyl bromide:bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl) sulfate;6-(1,3-butanedialkoxyethoxysilyl)-1-hexyl bromide;1-(1,3-butanedialkoxyethoxysilyl)-5-hexyl chloride;8-(1,3-butanedialkoxyethoxysilyl)-1-octyl bromide;10-(1,3-butanedialkoxyethoxysilyl)-1-decyl chloride;bis-(3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl) sulfate; andthe like.

In another embodiment, the cyclic and bridging dialkoxy haloalkylsilanes include, but are not limited to,3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride;3-(2-methyl-2,4-pentanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl chloride;3-(2-methyl-2,4-pentanedialkoxyphenylsilyl)-1-propyl chloride;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl chloride;3-(1,3-butanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,3-propanedialkoxyethoxysilyl)-1-propyl chloride;3-(1,3-propanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,2-propanedialkoxyethoxysilyl)-1-propyl chloride;3-(1,2-propanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,2-ethanedialkoxyisopropoxysilyl)-1-propyl chloride; 3-(neopentylglycoxyethoxysilyl)-1-propyl chloride; 3-(neopentylglycoxyisopropoxysilyl)-1-propyl chloride;3-(2,3-dimethyl-2,3-butanedialkoxyethoxysilyl)-1-propyl chloride;3-(2,2-diethyl-1,3-propanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyethoxysilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,3-butanedialkoxymethylsilyl)-1-propyl chloride; 3-(neopentylglycoxymethylsilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl chloride;3-(2-methyl-1,3-propanedialkoxyphenylsilyl)-1-propyl chloride;2-methyl-2,4-pentanedialkoxyethoxysilylmethyl chloride; and1,3-butanedialkoxyethoxysilylmethyl chloride and the like.

In one embodiment of the present invention, the cyclic and bridgingdialkoxy haloalkyl silanes include, but are not limited to,2-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride;2-(2-methyl-2,4-pentanedialkoxyisopropoxysilyl)-1-propyl chloride;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl chloride;3-(1,3-butanedialkoxyisopropoxysilyl)-1-propyl chloride and the like.

In one embodiment, the cyclic dialkoxy haloalkyl silanes are cyclic andbridging dialkoxy analogs of 3-chloro-1-propyltriethoxysilane(3-triethoxysilyl-1-propyl chloride), which is used as a starting pointfor the manufacture of silane coupling agents.

In another embodiment of the present invention, each occurrence of X isR. Representative examples of the cyclic and bridging dialkoxy blockedmercaptofunctional silanes of this embodiment include, but are notlimited to, 3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthioacetate; 2-methyl-2,4-pentanedialkoxyisopropylsilylmethylthioacetate; 6-(2-methyl-2,4-pentanedialkoxyethylsilyl)-1-hexylthioacetate; 1-(2-methyl-2,4-pentanedialkoxymethylsilyl)-5-hexylthioacetate; 8-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-octylthioacetate; 10-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-decylthioacetate; 3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthiooctanoate: 3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthiodecanoate; 3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthiododecanoate: 3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthio-2-methylheptanoate;bis-(3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl)dithioadipate; 3-(1,3-butanedialkoxybutylsilyl)-1-propyl thioacetate;3-(1,3-butanedialkoxyisopropylsilyl)-4-butyl thioacetate;6-(1,3-butanedialkoxymethylsilyl)-1-hexyl thioacetate;8-(1,3-butanedialkoxymethylsilyl)-1-octyl thioacetate;10-(1,3-butanedialkoxymethylsilyl)-1-decyl thioacetate;3-(1,3-butanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(1,3-butanedialkoxymethylsilyl)-1-propyl thiodecanoate;3-(1,3-butanedialkoxypropylsilyl)-1-propyl thiododecanoate;3-(2,2-dimethyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propyl thiodecanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propyl thiododecanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propylthiotetradecanoate; 3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thio-2-ethylhexanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propylthio-2-methylheptanoate; bis-(3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl) dithioadipate;neopentylglycoxypropylsilylmethyl thioacetate and the like.

In another embodiment, cyclic and bridging dialkoxy blockedmercaptofunctional silanes include, but are not limited tobis-(3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyl)methyldithiophosphonate;bis-(3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyl)ethyldithiophosphonate:3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyldimethylthiophosphinate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyldiethylthiophosphinate;tris-(3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyl)tetrathiophosphate;bis-(3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyl)methyltrithiophosphonate;bis-(3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyl)ethyltrithiophosphonate;3-(2-methyl-2,4-pentanedialkoxyethylsilyl-1-propyldimethyldithiophosphinate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propyldiethyldithiophosphinate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propylmethylthiosulphate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propylmethanethiosulphonate;3-(2-methyl-2,4-pentanedialkoxypropylsilyl-1-propylethanethiosulphonate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl-1-propylbenzenethiosulphonate;and the like.

The cyclic and bridging dialkoxy blocked mercaptofunctional silanecompositions included herein may comprise single components or variousmixtures of individual cyclic and bridging dialkoxy blockedmercaptofunctional silane components, blocked mercaptofunctional silanecomponents that comprise only monofunctional alkoxy groups, and whichoptionally include other species as well, including, for example, thosewherein synthetic methods result in a distribution of various silanesand those wherein mixtures of the starting components are employed forgenerating mixtures of cyclic and bridging dialkoxy blockedmercaptofunctional silane products. Moreover, it is to be understoodthat the partial hydrolyzates and/or condensates of these cyclic andbridging dialkoxy blocked mercaptofunctional silanes (i.e., cyclic andbridging dialkoxy blocked mercaptofunctional siloxanes and/or silanols)may also be encompassed by the silanes herein, in that these partialhydrolyzates and/or condensates will be a side product of most methodsof manufacture of the cyclic and bridging dialkoxy blockedmercaptofunctional silanes or can occur upon storage of the cyclic andbridging dialkoxy blocked mercaptofunctional silanes, especially inhumid conditions, or under conditions in which residual water remainingfrom their preparation is not completely removed subsequent to theirpreparation.

Likewise, the cyclic and bridging dialkoxy haloalkyl silane compositionsincluded herein may comprise single components or various mixtures ofindividual cyclic and bridging dialkoxy haloalkyl silane components,haloalkyl silane components which comprise only monofunctional alkoxygroups, and optionally including other species as well, including, forexample, those wherein synthetic methods result in a distribution ofvarious silanes and including those wherein mixtures of the startingcomponents are employed for generating mixtures of cyclic and bridgingdialkoxy haloalkyl and/or cyclic and bridging dialkoxy blockedmercaptofunctional silane products.

Moreover, it is to be understood that the partial hydrolyzates and/orcondensates of these cyclic and bridging dialkoxy haloalkyl silanes(i.e., cyclic and bridging dialkoxy haloalkyl siloxanes and/or silanols)may also be encompassed by the cyclic and bridging dialkoxy haloalkylsilanes herein, in that these partial hydrolyzates and/or condensateswill be a side product of most methods of manufacture of the cyclic andbridging dialkoxy haloalkyl silanes or can occur upon storage of thecyclic and bridging dialkoxy haloalkyl silanes, especially in humidconditions, or under conditions in which residual water remaining fromtheir preparation is not completely removed subsequent to theirpreparation.

Furthermore, partial to substantial hydrolysis and siloxane content ofthe cyclic and bridging dialkoxy blocked mercaptofunctional silanes areencompassed by the silanes described herein and may be deliberatelyprepared by incorporating the appropriate stoichiometry or an excess ofwater into the methods of preparation described herein for the silanes.Silane structures herein encompassing hydrolyzates and siloxanes aredescribed in the structures given in Formulae 1 and 2 wherein thesubscripts, v, of Z^(b)=(—O—)_(0.5) and/or u of X=OH are substantive(i.e., substantially larger than zero).

The cyclic and bridging dialkoxy blocked mercaptofunctional silanecompositions may be loaded on a carrier, or filler, such as, forexample, a porous polymer, carbon black, silica or the like, so thatthey are in a dry free flowing form for convenient delivery to rubber.In one embodiment, the carrier would be part of the inorganic filler tobe used in the rubber.

In one embodiment, a dry free flowing composition comprises a silane inaccordance with this invention in admixture with one or more of theaforesaid carrier materials. e.g., in a weight ratio of from about 0.1to about 60 weight percent. The BET surface area of such carriers assilica can vary widely and in one embodiment can vary from about 100m²/g to about 300 m²/g. Another property of such carriers is their DOPadsorption, an oil adsorption index. In the case of nonporous carrierssuch as silica, the DOP adsorption can range from about 100 ml/100 gm toabout 400 ml/100 gm. Porous carriers such as foamed polyolefins canadvantageously absorb from about 10 ml to about 250 ml/100 gm (fromabout 9 to about 70 weight percent) of the silane of the presentinvention.

The filler can be essentially inert to the silane with which it isadmixed as is the case with carbon black or organic polymers, or it canbe reactive therewith, e.g., the case with carriers possessing metalhydroxyl surface functionality, e.g., silicas and other silaceousparticulates which possess surface silanol functionality.

Manufacture of Cyclic and Bridging Dialkoxy Blocked MercaptofunctionalSilanes Anhydrous Methods

The methods for the preparation of the cyclic and bridging dialkoxyblocked mercaptofunctional silanes herein can involve esterification ofsulfur in a sulfur-comprising silane and direct incorporation of theblocked mercapto group into a silane, either by substitution of anappropriate leaving group or by addition across a carbon-carbon doublebond or can involve transesterification or ester exchange of thealkoxysilyl moieties of a blocked mercapto silane.

Illustrative examples of synthetic procedures for the preparation ofthioester silanes would include: Reaction 1) the reaction between amercaptosilane and an acid anhydride corresponding to the thioestergroup present in the desired product; Reaction 2) the reaction of analkali metal salt of a mercaptosilane with the appropriate acidanhydride or acid halide; Reaction 3) the transesterification between amercaptosilane and an ester, optionally using any appropriate catalystsuch as, for example, an acid, base, tin compound, titanium compound,transition metal salt, a salt of the acid corresponding to the ester andthe like; Reaction 4) the transesterification between a thioester silaneand another ester, optionally using any appropriate catalyst such as,for example, an acid, base, tin compound, titanium compound, transitionmetal salt, a salt of the acid corresponding to the ester and the like;Reaction 5) the transesterification between a 1-sila-2-thiacyclopentaneor a 1-sila-2-thiacyclohexane and an ester, optionally using anyappropriate catalyst such as, for example, an acid, base, tin compound,titanium compound, transition metal salt, a salt of the acidcorresponding to the ester and the like; Reaction 6) the free radicaladdition of a thioacid across a carbon-carbon double bond of analkene-functional silane, catalyzed by UV light, heat, or theappropriate free radical initiator wherein, if the thioacid is athiocarboxylic acid, the two reagents are brought into contact with eachother in such a way as to ensure that whichever reagent is added to theother is reacted substantially before the addition proceeds; andReaction 7) the reaction between an alkali metal salt of a thioacid witha haloalkylsilane under anhydrous conditions.

Acid halides for use herein include, but are not limited to, organicacid halides, inorganic acid halides, e.g., POT₃, SOT₂, SO₂T₂, COT₂,CST₂, PST₃ and PT₅ wherein T is a halide, and the like and mixturesthereof. Acid anhydrides, include, but are not limited to, organic acidanhydrides (and their sulfur analogs), inorganic acid anhydrides, e.g.,SO₃, SO₂, P₂O₅, P₂S₅, H₂S₂O₇, CO₂, COS, and CS₂, and the like andmixtures thereof.

Illustrative examples of synthetic procedures for the preparation ofcyclic and bridging dialkoxy blocked mercaptofunctional silanes include:Reaction 8) the reaction between a mercaptosilane and a carboxylic acidanhydride corresponding to the thiocarboxylate group present in thedesired product; Reaction 9) reaction of an alkali metal salt of amercaptosilane with the appropriate carboxylic acid anhydride or acidhalide; Reaction 10) the transesterification between a mercaptosilaneand a carboxylate ester, optionally using any appropriate catalyst suchas, for example, an acid, base, tin compound, titanium compound,transition metal salt, a salt of the acid corresponding to thecarboxylate ester and the like; Reaction 11) the transesterificationbetween a thiocarboxylate-functional silane and another ester,optionally using any appropriate catalyst such as, for example, an acid,base, tin compound, titanium compound, transition metal salt, a salt ofthe acid corresponding to the other ester and the like; Reaction 12) thetransesterification between a 1-sila-2-thiacyclopentane or a1-sila-2-thiacyclohexane and a carboxylate ester, optionally using anyappropriate catalyst such as, for example, an acid, base, tin compound,titanium compound, transition metal salt, a salt of the acidcorresponding to the carboxylate ester and the like; Reaction 13) thefree radical addition of a thiocarboxylic acid across a carbon-carbondouble bond of an alkene-functional silane, catalyzed by UV light, heat,or the appropriate free radical initiator; Reaction 14) the reactionbetween an alkali metal salt of a thiocarboxylic acid with ahaloalkylsilane under anhydrous conditions; Reaction 15) thetransesterification between the alkoxysilyl moieties of athiocarboxylate silane and a diol, catalyzed by an acid or a base,titanium alkoxide or chelate, or zirconium alkoxide or chelate; andReaction 16) the continuous transesterification between the alkoxysilylmoieties of a thiocarboxylate silane and a diol, catalyzed by an acid ora base, titanium alkoxide or chelate, or zirconium alkoxide or chelate,conducted simultaneously with distillation, e.g., thin filmdistillation.

Reactions 1 and 8 could be carried out by distilling a mixture of themercaptosilane and the acid anhydride and optionally a solvent.Appropriate boiling temperatures of the mixture can range from about 50to about 250° C. and all subranges therebetween. In one embodiment, theboiling temperature can range from about 60 to about 200° C. and allsubranges therebetween. In another embodiment, the boiling temperaturecan range from about 70 to about 170° C. and all subranges therebetween.This process leads to a chemical reaction in which the mercapto group ofthe mercaptosilane is esterified to the thioester silane analog withrelease of an equivalent of the corresponding acid. The acid typicallyis more volatile than the acid anhydride. The reaction is driven by theremoval of the more volatile acid by distillation. For the more volatileacid anhydrides, e.g., acetic anhydride, the distillation can be carriedout at ambient pressure to reach temperatures sufficient to drive thereaction toward completion. For less volatile materials solvents, e.g.,toluene, xylene, glyme and diglyme, could be used with the process tolimit temperature. Alternatively, the process could be run at reducedpressure. It can be advantageous to use up to a two-fold excess or moreof the acid anhydride which would be distilled out of the mixture afterall of the more volatile reaction coproducts, consisting of acids andnon-silane esters, have been distilled out. This excess of acidanhydride would serve to drive the reaction to completion, as well as tohelp drive the coproducts out of the reaction mixture. At the completionof the reaction, distillation should be continued to drive out theremaining acid anhydride. The product optionally could be distilled.

Reactions 2 and 9 can be carried out in two steps. The first stepinvolves at least the conversion of the mercaptosilane to acorresponding metal derivative, e.g., alkali metal derivatives suchsodium, potassium or lithium. The metal derivative can generally beprepared by adding the alkali metal or a strong base derived from thealkali metal to the mercaptosilane. The reaction can occur at ambienttemperature. Useful bases include, but are not limited to, alkali metalalkoxides, amides, hydrides, mercaptides. Alternatively, alkali metalorganometallic reagents or grignard reagents which would yield magnesiumderivatives) may also be used. Solvents such as, for example, toluene,xylene, benzene, aliphatic hydrocarbons, ethers, alcohols and the likecould be used to prepare the alkali metal derivatives. Once the alkalimetal derivative is prepared, any alcohol present would need to beremoved. This could be done by distillation or evaporation. Alcoholssuch as methanol, ethanol, propanol, isopropanol, butanol, isobutanol,and t-butanol may be removed by azeotropic distillation with benzene,toluene, xylene, or aliphatic hydrocarbons. In one embodiment, tolueneand xylene are used. In another embodiment, toluene is used. The secondstep in the overall process would be to add to this solution, withstirring, the acid chloride or acid anhydride at temperatures between−20° C. and the boiling point of the mixture; and at temperaturesbetween 0° C. and ambient temperature in another embodiment. The productwould be isolated by removing the salt and solvent. It could be purifiedby distillation.

Reactions 3 and 10 could be carried out by distilling a mixture of themercaptosilane and the ester and optionally a solvent and/or a catalyst.Appropriate boiling temperatures of the mixture would be above about100° C. This process leads to a chemical reaction in which the mercaptogroup of the mercaptosilane is esterified to the thioester silane analogwith release of an equivalent of the corresponding alcohol. The reactionis driven by the removal of the alcohol by distillation, either as themore volatile species, or as an azeotrope with the ester. For the morevolatile esters the distillation is suitably carried out at ambientpressure to reach temperatures sufficient to drive the reaction towardcompletion. For less volatile esters, solvents, such as toluene, xylene,glyme, and diglyme could be used with the process to limit temperature.Alternatively, the process could be run at reduced pressure. It can beadvantageous to use up to a two-fold excess or more of the ester, whichwould be distilled out of the mixture after all of the alcohol coproducthas been distilled out. This excess ester would serve to drive thereaction to completion as well as to help drive the coproduct alcoholout of the reaction mixture. At the completion of the reaction,distillation would be continued to drive out the remaining ester. Theproduct optionally could be distilled.

Reactions 4 and 11 could be carried out by distilling a mixture of thethioester silane and the other ester and optionally a solvent and/or acatalyst. Appropriate boiling temperatures of the mixture would be aboveabout 80° C.; and usually above about 100° C. In one embodiment, thetemperature may not exceed about 250° C. This process leads to achemical reaction in which the thioester group of the thioester silaneis transesterified to a new thioester silane with release of anequivalent of a new ester. The new thioester silane generally would bethe least volatile species present; however, the new ester would be morevolatile than the other reactants. The reaction would be driven by theremoval of the new ester by distillation. The distillation can becarried out at ambient pressure to reach temperatures sufficient todrive the reaction toward completion. For systems using only lessvolatile materials, solvents, such as toluene, xylene, glyme, anddiglyme could be used with the process to limit temperature.Alternatively, the process could be run at reduced pressure. It could beadvantageous to use up to a two-fold excess or more of the other ester,which would be distilled out of the mixture after all of the new estercoproduct has been distilled out. This excess other ester would serve todrive the reaction to completion as well as to help drive the co-productother ester out of the reaction mixture. At the completion of thereaction, distillation would be continued to drive out the remainingsaid new ester. The product optionally then could be distilled.

Reactions 5 and 12 could be carried out by heating a mixture of the1-sila-2-thiacyclopentane or the 1-sila-2-thiacyclohexane and the esterwith the catalyst. Optionally, the mixture could be heated or refluxedwith a solvent. In another embodiment, a solvent whose boiling pointmatches the desired temperature is used. Optionally, a solvent of higherboiling point than the desired reaction temperature can be used atreduced pressure, the pressure being adjusted to bring the boiling pointdown to the desired reaction temperature. The temperature of the mixturecan be in the range of about 80 to about 250° C. and all subrangestherebetween. In another embodiment, the temperature can range fromabout 100 to about 200° C. and all subranges therebetween. Solvents,such as toluene, xylene, aliphatic hydrocarbons, and diglyme could beused with the process to adjust the temperature. Alternatively, theprocess could be run under reflux at reduced pressure. In oneembodiment, the condition is to heat a mixture of the1-sila-2-thiacyclopentane or the 1-sila-2-thiacyclohexane and the ester,without solvent, optionally under inert atmosphere, for a period ofabout 20 to about 100 hours and all subranges therebetween and at atemperature of about 120 to about 170° C. and all subranges therebetweenusing the sodium, potassium, or lithium salt of the acid correspondingto the ester as a catalyst. The process leads to a chemical reaction inwhich the sulfur-silicon bond of the 1-sila-2-thiacyclopentane or the1-sila-2-thiacyclohexane is transesterified by addition of the esteracross said sulfur-silicon bond. The product is the thioester silaneanalog of the original 1-sila-2-thiacyclopentane or the1-sila-2-thiacyclohexane. Optionally, up to a two-fold excess or more ofthe ester could be used to drive the reaction toward completion. At thecompletion of the reaction, the excess ester can be removed by, e.g.,distillation. The product optionally could be purified by distillation.

Reactions 6 and 13 can be carried out by heating or refluxing a mixtureof the alkene-functional silane and the thioacid. Aspects of Reaction 13have been disclosed previously in U.S. Pat. No. 3,692,812 and by G. A.Gornowicz et al. in J. Org. Chem. (1968), 33(7), 2918-24. Theuncatalyzed reaction may occur at temperatures as low as about 105° C.In another embodiment, the temperature may exceed about 160° C. Thereaction may be made reliable and the reaction brought largely tocompletion by using UV radiation or a catalyst. With a catalyst, thereaction can be made to occur at temperatures below about 90° C. Usefulcatalysts are free radical initiators, e.g., peroxides, such as organicperoxides, and azo compounds. Examples of peroxide initiators includeperacids, such bybenzoic and peracetic acids; esters of peracids;hydroperoxides, such as t-butyl hydroperoxide; peroxides, such asdi-t-butyl peroxide; and peroxy-acetals and ketals, such as1,1-bis(t-butylperoxy)cyclohexane, or any other peroxide. Examples ofazo initiators include azobisisobutyronitrile (AIBN);1,1′-azobis(cyclohexanecarbonitrile) (VAZO; DuPont product); andazo-tert-butane.

The reaction can be run by heating a mixture of the alkene-functionalsilane and the thioacid with the catalyst. In one embodiment, theoverall reaction can be run on an equimolar or near equimolar basis tothe highest conversions. The reaction is sufficiently exothermic that ittends to lead to a rapid temperature increase to reflux followed by avigorous reflux as the reaction initiates and continues rapidly. Thisvigorous reaction can lead to hazardous boilovers for larger quantities.Side reactions, contamination, and loss in yield can result as well fromuncontrolled reactions.

The reaction can be controlled effectively by adding partial quantitiesof one reagent to the reaction mixture, initiating the reaction with thecatalyst, allowing the reaction to run its course largely to completion,and then adding the remainder of the reagent, either as a singleaddition or as multiple additives. The initial concentrations and rateof addition and number of subsequent additions of the deficient reagentdepend on the type and amount of catalyst used, the scale of thereaction, the nature of the starting materials, and the ability of theapparatus to absorb and dissipate heat. A second way of controlling thereaction would involve the continuous addition of one reagent to theother with concomitant continuous addition of catalyst. Whethercontinuous or sequential addition is used, the catalyst can be addedalone and/or pre-blended with one or both reagents, or combinationsthereof. In one embodiment, two methods may be used for reactionsinvolving thiolacetic acid and alkene-functional silanes having terminalcarbon-carbon double bonds. The first method involves initially bringingthe alkene-functional silane to a temperature of about 160 to about 180°C. and all subranges therebetween, or to reflux, whichever temperatureis lower. The first portion of thiolacetic acid can be added at a rateas to maintain up to a vigorous, but controlled reflux. Foralkene-functional silanes with boiling points above about 100 to about120° C. this reflux results largely from the relatively low boilingpoint of thiolacetic acid (about 88 to about 92° C. depending on purity)relative to the temperature of the alkene-functional silane.

At the completion of the addition, the reflux rate rapidly subsides. Itoften accelerates again within several minutes, especially if analkene-functional silane with a boiling point above about 120° C. isused, as the reaction initiates. If it does not initiate within about 10to about 15 minutes, initiation can be brought about by addition ofcatalyst. In one embodiment, the catalyst is di-t-butyl peroxide. Theappropriate quantity of catalyst is from about 0.2 to about 2 percentand all subranges therebetween of the total mass of mixture to which thecatalyst is added. In another embodiment, the quantity of catalyst canrange from about 0.5 to about 1 percent and all subranges therebetweenof the total mass of mixture to which the catalyst is added. Thereaction typically initiates within a few minutes as evidenced by anincrease in reflux rate. The reflux temperature gradually increases asthe reaction proceeds. Then the next portion of thiolacetic acid isadded, and the aforementioned sequence of steps are repeated. The numberof thiolacetic additions for total reaction quantities of about one toabout four kilograms can be two, with about one-third of the totalthiolacetic acid used in the first addition and the remainder in thesecond. For total quantities in the range of about four to tenkilograms, a total of three thiolacetic additions can be used, thedistribution being about 20 percent of the total used in the firstaddition, about 30 percent in the second addition, and the remainder inthe third addition. For larger scales involving thiolacetic acid andalkene-functional silanes, it is advantageous to use more than a totalof three thiolacetic additions and more advantageous, to add thereagents in the reverse order. Initially, the total quantity ofthiolacetic acid is brought to reflux. This is followed by continuousaddition of the alkene-functional silane to the thiolacetic acid at sucha rate as to bring about a smooth, but vigorous, reaction rate.

The catalyst, e.g., di-t-butylperoxide, can be added in small portionsduring the course of the reaction or as a continuous flow. It is best toaccelerate the rate of catalyst addition as the reaction proceeds tocompletion to obtain the highest yields of product for the lowest amountof catalyst required. The total quantity of catalyst used should beabout 0.5 to about 2 percent of the total mass of reagents used.Whichever method is used, the reaction is followed up by a vacuumstripping process to remove volatiles and unreacted thiolacetic acid andsilane. The product may be purified by distillation.

Methods to run Reactions 7 and 14 can generally be carried out in twosteps. The first step involves preparation of a salt of the thioacid. Inone embodiment, alkali metal derivatives are used, e.g., sodiumderivatives. These salts can be prepared as solutions in solvents inwhich the salt is appreciably soluble, but suspensions of the salts assolids in solvents in which the salts are only slightly soluble can alsobe used. Alcohols, such as methanol, ethanol, propanol, isopropanol,butanol, isobutanol, t-butanol and the like are useful because thealkali metal salts are slightly soluble in them. In cases where thedesired product is an alkoxysilane, it is advantageous to use an alcoholcorresponding to the silane alkoxy group to prevent transesterificationat the silicon ester. Alternatively, nonprotic solvents can be used.Examples of appropriate solvents are ethers or polyethers such as, forexample, glyme, diglyme, and dioxanes: N,N′-dimethylformamide;N,N′-dimethylacetamide; dimethylsulfoxide; N-methylpyrrolidinone;hexamethylphosphoramide and the like. Once a solution, suspension, orcombination thereof of the salt of the thioacid has been prepared, thesecond step is to react it with the appropriate haloalkylsilane. Thismay be accomplished by stirring a mixture of the haloalkylsilane withthe solution, suspension, or combination thereof of the salt of thethioacid at temperatures corresponding to the liquid range of thesolvent for a period of time sufficient to complete substantially thereaction. In one embodiment, temperatures are those at which the salt isappreciably soluble in the solvent and at which the reaction proceeds atan acceptable rate without excessive side reactions. With reactionsstarting from chloroalkylsilanes in which the chlorine atom is notallylic or benzylic, temperatures and range from about 60 to about 160°C. and all subranges therebetween. Reaction times can range from one orseveral hours to several days. For alcohol solvents where the alcoholpossesses four carbon atoms or fewer, the temperature can be at or nearreflux. When using diglyme as a solvent, the temperature can range fromabout 70 to about 120° C. and all subranges therebetween, depending onthe thioacid salt used. If the haloalkylsilane is a bromoalkylsilane ora chloroalkylsilane in which the chlorine atom is allylic or benzylic,temperature reductions of about 30 to about 60° C. and all subrangestherebetween are appropriate relative to those appropriate fornonbenzylic or nonallylic chloroalkylsilanes because of the greaterreactivity of the bromo group. In one embodiment, bromoalkylsilanes areused because of their greater reactivity, lower temperatures required,and greater ease in filtration or centrifugation of the coproduct alkalimetal halide. This, however, can be overridden by the lower cost of thechloroalkylsilanes, especially for those having the halogen in theallylic or benzylic position. For reactions between straight chainchloroalkylethoxysilanes and sodium thiocarboxylates to formthiocarboxylate ester ethoxysilanes, ethanol can be used at reflux forabout 10 to about 20 hours and all subranges therebetween if 5 to 20%mercaptosilane is acceptable in the product. Otherwise, diglyme can beused in which the reaction can be carried out at a temperature in therange of about 80 to about 120° C. and all subranges therebetween forabout one to about three hours and all subranges therebetween. Uponcompletion of the reaction, the salts and solvent should be removed andthe product may be distilled to achieve higher purity.

If the salt of the thioacid to be used in Reactions 7 and 14 is notcommercially available, its preparation may be accomplished by one oftwo methods, described below as Method A and Method B. Method A involvesadding the alkali metal or a base derived from the alkali metal to thethioacid. The reaction occurs at ambient temperature. Useful basesinclude, but are not limited to, alkali metal alkoxides, hydrides,carbonate, bicarbonate and the like and mixtures thereof. Solvents, suchas toluene, xylene, benzene, aliphatic hydrocarbons, ethers, andalcohols may be used to prepare the alkali metal derivatives. In MethodB, acid chlorides or acid anhydrides would be converted directly to thesalt of the thioacid by reaction with the alkali metal sulfide orhydrosulfide. Hydrated or partially hydrous alkali metal sulfides orhydrosulfides are available, however, anhydrous or nearly anhydrousalkali metal sulfides or hydrosulfides can also be used. Hydrousmaterials can be used, however, but with loss in yield and hydrogensulfide formation as a co-product. The reaction involves addition of theacid chloride or acid anhydride to the solution or suspension of thealkali metal sulfide and/or hydrosulfide and heating at temperaturesranging from ambient to the reflux temperature of the solvent for aperiod of time sufficient to largely complete the reaction, as evidencedby the formation of the co-product salts.

If the alkali metal salt of the thioacid is prepared in such a way thatan alcohol is present, either because it was used as a solvent, orbecause it was formed, for example, by the reaction of a thioacid withan alkali metal alkoxide, it may be desirable to remove the alcohol if aproduct low in mercaptosilane is desired and if loss of diol fromsilicon is to be prevented. In this case, it would be necessary toremove the alcohol prior to reaction of the salt of the thioacid withthe haloalkylsilane. This could be done by distillation or evaporation.Alcohols such as methanol, ethanol, propanol, isopropanol, butanol,isobutanol, and t-butanol can be removed by, for example, azeotropicdistillation with benzene, toluene, xylene, or aliphatic hydrocarbons.In one embodiment, toluene and xylene are used.

Reaction 15 can be carried out by at least reacting a catalyzed mixtureof a thiocarboxylate-alkoxy silane and a diol with simultaneousdistillation. The reaction leads to the alcohol exchange of one or moreof the alkoxy groups selectively at the silicon atom of thethiocarboxylate silane with the diol. The reaction is driven by theremoval of the more volatile alcohol by distillation. In one embodiment,the catalysts are acids. Suitable acid catalysts include, but are notlimited to, p-toluenesulfonic acid, sulfuric acid, hydrochloric acid,chlorosilanes, chloroacetic acids, phosphoric acid, and the like andmixtures thereof. In another embodiment, base catalysts are used.However, base catalysts are less desirable as they have been found to beless efficient. For example, sodium ethoxide is active, but causes somedegradation of the thiocarboxylate silane. In another embodiment,titanium alkoxides or chelates and zirconium alkoxides or chelates areused as catalysts.

Examples of diols that are capable of transesterification of thealkoxysilyl groups include, but are not limited 1,2-ethylene glycol,neopentyl glycol, 1,2-propanediol, 1,3-propanediol,2-methyl-1,3-propanediol, 1,3-butanediol, 2-methyl-2,4-pentanediol,1,4-butanediol, 1,6-hexanediol, cyclohexane dimethanol, pinacol and thelike and mixtures thereof.

Reaction 16 could be carried out by continuously premixing theflow-streams of thiocarboxylate-alkoxy silane, diol and catalyst atappropriate ratios and then introducing the premixed reactants into areactive distillation system, e.g., a thin film distillation deviceoperating at the desired reaction temperature and partial vacuumconditions. Conducting the reaction in a thin film at low pressure canaccelerate the removal of the alcohol byproduct and improve thetransesterification reaction rate. The vaporization and removal of thealcohol byproduct from the film shifts the chemical equilibrium of thereaction to favor formation of the desired product and minimizesundesired side reactions.

Preparation of Cyclic and Bridging Dialkoxy Blocked MercaptofunctionalSilanes Aqueous Method for Thiocarboxylate Silanes

The preparation of the cyclic and bridging dialkoxy blockedmercaptofunctional silanes generally involves at least the reactionbetween an aqueous solution of a salt of a thiocarboxylic acid or other(thus, an aqueous solution of a thiocarboxylate salt, which wouldpossess the thiocarboxylate anion) with a cyclic and bridging dialkoxyhaloalkyl silane, in the presence or absence of a phase transfercatalyst. Optionally, mixtures comprising aqueous thiocarboxylate saltsand/or cyclic and bridging dialkoxy haloalkyl silanes may be used, fromwhich mixtures comprising cyclic and bridging dialkoxy blockedmercaptofunctional silanes may be prepared. The cyclic and bridgingdialkoxy haloalkyl silanes may themselves be used as mixtures withhaloalkyl silanes, thereby yielding products comprising mixturescomprising cyclic and bridging dialkoxy blocked mercaptofunctionalsilanes with thiocarboxylate or thioester silanes comprising onlymonofunctional alkoxy groups. As used herein, the term “cyclic andbridging dialkoxy haloalkyl silane” refers to any silane whose structurecan be represented by Formula 3, first given above. The term “haloalkylsilane” as used herein refers to any silane whose structure can berepresented by Formula 6 below. Collectively, the cyclic and bridgingdialkoxy haloalkyl silanes and haloalkyl silanes will herein be referredto as “alkoxy haloalkyl silanes”. Thus, the terms “cyclic and bridgingdialkoxy haloalkyl silane”, “haloalkyl silane”, and “alkoxy haloalkylsilane”, as used herein, would include single components or mixturescomprising silanes with one or more halogen substitutions for hydrogenon their hydrocarbon groups, as well as other substitutions that wouldrepresent potential leaving groups during nucleophilic substitutionreactions, as described below.

Structures for the cyclic and bridging dialkoxy haloalkyl silanes andhaloalkyl silanes are given in Formulae 3 and 6, respectively,

L_(r)-G-(SiX_(u)Z^(b) _(v)Z^(c) _(w))_(s)  (Formula 3),

L_(r)-G-(SiX₃)_(s)  (Formula 6)

and structures for the thiocarboxylate salts are given in Formulae 7, 8and 9, respectively,

G(—Y¹-SM)_(d)  (Formula 7)

[(ROC(═O))_(p)-(G)_(j)]-Y¹-SM and  (Formula 8)

[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]-Y¹-SM  (Formula 9)

wherein

each occurrence of M is independently an alkali metal; ammonium; or amono-, di-, or tri-substituted ammonium;

each occurrence of Y¹ is independently carbonyl, d is 1 to about 6 andR, L, G, X, Z^(b), Z^(c), j, p, q, u, v, w, r and s have the aforestatedmeanings.

M can be an alkali metal; ammonium; or a mono-, di-, or tri-substitutedammonium. Thus, M can be a monocation, meaning it occurs as a cation,typically with a single positive charge. Dicationic ions could also beused in cases where their thiocarboxylate salts are available and aresufficiently solubile in water. As such, M is the counterion to theanionic thiocarboxylate such as G(-Y¹—S⁻)_(d). Representative examplesof M include, but are not limited to, sodium, potassium, ammonium,methyl ammonium, and triethyl ammonium. In one embodiment, sodium,potassium, or ammonium are used. In another embodiment. M is sodium.

L can be a halogen atom (i.e., F, Cl, Br, or I), sulfonate group,sulfinate group, or carboxylate group. From a synthetic chemicalstandpoint, L is any group that can function as a leaving group duringnucleophilic substitution reactions. Representative examples of L arechloride, bromide, toluenesulfonate, benzenesulfonate, andmethanesulfonate. L could even be a divalent group such as sulfate orphosphate. In one embodiment, L is chloro or bromo. In anotherembodiment, L is chloro.

The preparation of the cyclic and bridging dialkoxy blockedmercaptofunctional silane compositions can be carried out by addition ofthe alkoxy haloalkyl silane to an aqueous solution of thethiocarboxylate salt and agitating the mixture until the reaction hasreached the desired level of completeness. Additional salts mayoptionally be present or be added to the aqueous thiocarboxylate salt toincrease the ionic strength of the solution so as to further stabilizethe silanes against hydrolysis. The level of completeness of thereaction may be monitored by any means that distinguishes the reactantsfrom the products, such as, for example, gas chromatography (GC), liquidchromatography (LC or HPLC), nuclear magnetic resonance spectroscopy(NMR), or infrared spectroscopy (IR) of the organic phase, or wetchemical analysis of the aqueous phase. A phase transfer catalyst may beadded in one or several doses and/or in a continuous manner to thethiocarboxylate salt, the alkoxy haloalkyl silane, and/or the reactionmixture before, during, and/or after the addition of the alkoxyhaloalkyl silane to the aqueous thiocarboxylate salt, to accelerate thereaction.

Appropriate reaction conditions comprise temperatures from about −30 toabout 300° C. and either pressures from ambient to about 100 atmospheresor vacua from ambient to about 0.01 torr. In one embodiment, theconditions are from about −10 to about 100° C. at ambient pressure. Inanother embodiment, the reaction temperatures are from about 25 to about95° C. In yet another embodiment, reaction temperatures are from about40 to about 85° C. Variable temperatures within the aforementionedranges may be employed, as, for example, a gradual upward or downwardramping of the temperature during the course of the reaction.

Appropriate concentrations of the starting aqueous thiocarboxylate saltsare from about 1 weight percent to saturation and all subrangestherebetween, which can be as high as about 50 weight % or more. Inanother embodiment, concentrations are from about 20 to about 45 weight% and all subranges therebetween. In another embodiment, concentrationsare from about 30 to about 40 weight % and all subranges therebetween.Optionally, an excess of the thiocarboxylate salt, relative to thatdemanded by the reaction stoichiometry, may be used to drive thereaction to completion so as to obtain a product of minimal residualalkoxy haloalkyl silane starting material, to obtain the product withminimal reaction time and/or temperature, and/or to obtain a productwith minimal loss to or contamination by silane hydrolysis/condensationproducts. Alternatively, an excess of the alkoxy haloalkyl silane,relative to that demanded by the reaction stoichiometry, may be used toreduce the residual aqueous thiocarboxylate salt content at thecompletion of the reaction to a minimum.

The reactions may be run neat (i.e., without solvent) or in the presenceof one or more solvents which are insoluble or have limited solubilityin water. Useful solvents are ethers, for example, diethyl ether;hydrocarbons, for example, hexane, petroleum ether, toluene, and xylene;and ketones, for example, methyl ethyl ketone. In one embodiment,toluene or xylene are used. In one embodiment, the reaction is carriedout in the absence of solvent (neat).

Upon completion of the reaction, the agitation is terminated, resultingin the segregation of the reaction mixture into two liquid phases. Theorganic phase (typically the upper phase) comprises the cyclic andbridging dialkoxy blocked mercaptofunctional silane product, and theaqueous phase comprises the co-produced salts plus any salts initiallypresent or subsequently added to increase the ionic strength. If astarting aqueous solution of sufficient concentration was used, a solidphase may also separate comprising precipitated or crystallized salts.These salts may optionally be dissolved by addition of water so as toobtain a mixture comprising of mainly or exclusively two liquid phases.These phases can then be separated by decantation. Any solvents usedduring the process may then be removed by distillation or evaporation.Residual water may be removed by vacuum and/or heat stripping. Residualparticulates may subsequently or concurrently be removed by filtration.Residual alkoxy haloalkyl silanes may be removed by stripping with agood vacuum at elevated temperatures.

Preparation of the Aqueous Thiocarboxylate Salts

If an aqueous solution of the thiocarboxylate salt(s) required for thepreparation of the cyclic and bridging dialkoxy blockedmercaptofunctional silane composition is not available, it may beprepared in a separate step preceeding its use in the preparation of thecyclic and bridging dialkoxy blocked mercaptofunctional silanecomposition. Alternatively, the aqueous thiocarboxylate salt may beprepared in situ and used directly thereafter, as described above, toprepare the cyclic and bridging dialkoxy blocked mercaptofunctionalsilane composition.

If the thiocarboxylate salt is available, the aqueous solution thereofcan simply be prepared by dissolving an effective amount of the saltinto an effective amount of water to get a solution of the desiredconcentration, or it can be prepared by dilution or evaporativeconcentration of whatever solution is available. Alternatively, thedesired thiocarboxylate salt or aqueous solution thereof can be preparedfrom another salt of the desired thiocarboxylic acid. If thethiocarboxylic acid is available, the thiocarboxylate salt or aqueoussolution thereof can simply be prepared by neutralizing the acid with anappropriate base.

However, if neither the desired thiocarboxylic acid or one of its saltsis available, it can be prepared by synthesis of the thiocarbonyl groupby reaction of the appropriate acid halide and/or acid anhydride (e.g.,acid chloride) with an aqueous solution of a sulfide, a hydrosulfide, ora mixture thereof (e.g., aqueous sodium hydrosulfide, NaSH), to yield anaqueous solution of the thiocarboxylate salt. If an aqueous mixture ofthiocarboxylate salts is desired, the component thiocarboxylate saltscan be blended or the appropriate mixture of acid halides and/or acidanhydrides can be used in the preparation of the thiocarboxylate salts.Mixtures of one or more acid halides and/or one or more acid anhydridescan optionally be used, as can mixtures of different sulfides and/orhydrosulfides when preparing either single-component or mixtures ofaqueous thiocarboxylate salts.

Structures for the sulfides, hydrosulfides, and acid halides and acidanhydrides are given in Formulae 10-14, respectively,

M₂S  (Formula 10)

MSH  (Formula 11)

G(-Y¹-L)_(d)  (Formula 12)

[(ROC(═O))_(p)-(G)_(j)]-Y¹-L and  (Formula 13)

[(Z^(c) _(w)Z^(b) _(v)X_(u)Si)_(q)-G]-Y¹-L  (Formula 14)

wherein M, Z^(c), Z^(b), X, R, Y¹, G, L and d, j, p, q, u, v and w havethe aforestated meanings.

In the descriptions of the preparation of aqueous thiocarboxylate saltsolutions that follow, it is to be understood that, herein:

-   -   1) The term “acid halide” shall refer to the acid fluoride, acid        chloride, acid bromide, acid iodide, acid anhydride, or mixed        acid anhydride with another carboxylic acid, other organic acid,        or an inorganic acid; or any mixture thereof;    -   2) The term “sulfide” shall refer to an alkali metal, ammonium,        or substituted ammonium sulfide salt; or any mixture thereof;        and    -   3) The term “thiocarboxylate salt” shall refer to a        single-component or mixture of salts of one or more than one        thiocarboxylate and/or counterion (cation).

The preparation of the aqueous thiocarboxylate salts is carried out byaddition of the acid halide to an aqueous solution of the sulfide and/orhydrosulfide, and agitating the mixture. A phase transfer catalyst maybe added in one or several doses and/or in a continuous manner to theaqueous sulfide and/or hydrosulfide solution, the acid halide, and/orthe reaction mixture before, during, and/or after the addition of theacid halide to the aqueous sulfide and/or hydrosulfide solution, toaccelerate the reaction. Appropriate reaction conditions are attemperatures from about −30 to about 250° C. and all subrangestherebetween and either pressures of ambient to about 100 atmospheresand all subranges therebetween or vacuum from ambient to about 0.01 torrand all subranges therebetween. In another embodiment, the reactionconditions are from about −10 to about 100° C. and all subrangestherebetween at about ambient pressure. In another embodiment, reactiontemperatures are from about 20 to about 95° C. and all subrangestherebetween. In another embodiment, reaction temperatures are fromabout 25 to about 85° C. and all subranges therebetween. Variabletemperatures within the aforementioned ranges may be employed, as, forexample, a gradual upward or downward ramping of the temperature duringthe course of the reaction, or simply allowing the temperature to riseas a result of the reaction exotherm. Appropriate concentrations of thestarting aqueous sulfide and/or hydrosulfides are from about 1 weightpercent to saturation, which can be as high as about 60 weight % ormore. In another embodiment, concentrations are from about 10 to about40 weight % and all subranges therebetween. In another embodiment,concentrations are from about 15 to about 25 weight % and all subrangestherebetween. The reaction is usually complete when the acid halide hasdissolved in the aqueous phase, an exotherm is no longer evident fromthis reaction, and the evolution of any hydrogen sulfide subsides.Additional salts may optionally be present or be added to the aqueousthiocarboxylate salt to increase the ionic strength of the solution. Atthe completion of the reaction, the solution may optionally be filtered,if necessary, to remove particulate impurities and/or crystallizedcoproduced salts.

Preparation of the Aqueous Sulfides and/or Hydrosulfides

These solutions can be obtained by dissolving the appropriate quantityof sulfide or hydrosulfide, or the appropriate quantity of each if amixture is desired, into the appropriate quantity of water to obtain thedesired concentration of sulfide and/or hydrosulfide. Alternatively,these solutions can be prepared by addition of hydrogen sulfide to anaqueous solution of the appropriate base. A ratio of about one or moremoles of hydrogen sulfide to about one equivalent of base would yieldthe hydrosulfide, whereas a ratio of about one mole of hydrogen sulfideto about two equivalents of base would yield the sulfide. Ratios of onemole of hydrogen sulfide to between one and two equivalents of basewould yield the corresponding mixtures of the hydrosulfide and sulfide.

Alternatively, an aqueous solution of sulfide can also be prepared byaddition of about one equivalent of base to about one equivalent ofaqueous hydrosulfide, and an aqueous solution of hydrosulfide can alsobe prepared by addition of about one or more equivalents of hydrogensulfide to about one equivalent of aqueous sulfide. For example, aqueoussodium hydrosulfide could be prepared by addition of one mole or anexcess of hydrogen sulfide to an aqueous solution comprising one mole ofsodium hydroxide or sodium sulfide, and aqueous sodium sulfide could beprepared by addition of one mole of hydrogen sulfide or two moles ofsodium hydrosulfide to an aqueous solution comprising two moles ofsodium hydroxide.

The phase transfer catalysts used herein can accelerate the preparationsby facilitating chemical reactions across the phase boundary of twoimmiscible liquids. The phase transfer catalysts can comprise anysubstance capable of facilitating transfer of reacting species, whethermolecules or ions, across the phase boundary. Useful catalysts can beorganic cations, which are capable of transferring sulfur anions, suchas sulfide, hydrosulfide, and thiocarboxylate, from the aqueous phaseinto the organic phase, where these anions can then react with speciesin the organic phase, such as acid halides and haloalkyl silanes. Theorganic cations can be added as salts, or as concentrated or dilutesolutions in water and/or other suitable solvents, such as alcohols. Awide variety of anions can be associated with the organic cations, e.g.,fluoride, chloride, bromide, iodide, sulfate, bisulfate, carbonate,bicarbonate, hydroxide, phosphate, carboxylate, thiocarboxylate, and thelike.

In one embodiment, the phase transfer catalysts may be represented bygeneral Formula 15:

(R⁶R⁷R⁸R⁹N⁺)_(m)A^(−m)  (Formula 15)

wherein

-   -   each separate occurrence of R⁶, R⁷, R⁸ and R⁹, is independently        R;    -   N is nitrogen;    -   A^(−m) is a monovalent or polyvalent anion, where the minus sign        denotes that the species is an anion, and m denotes the number        of negative charges on the anion;    -   the subscript m is a positive integer of from 1 to about 6.

Representative examples of R⁶, R⁷, R⁸, and R⁹ include, but are notlimited to, branched and straight-chain alkyls, e.g., methyl, ethyl,propyl, isopropyl, butyl, isobutyl, hexyl, octyl, decyl, dodecyl,tetradecyl, octadecyl, phenyl, benzyl, tolyl, cyclohexyl,methylcyclohexyl, and allyl. In one embodiment, R⁶, R⁷, R⁸, and R⁹ areindependently selected from methyl, ethyl, butyl, and octyl.

Representative examples of A^(−m) include, but are not limited to,fluoride, chloride, bromide, iodide, sulfate, bisulfate, carbonate,bicarbonate, hydroxide, phosphate, carboxylate, and thiocarboxylate,sulfide, hydrosulfide and the like. In one embodiment, A is chloride. Inanother embodiment, A^(−m) is bromide. In another embodiment, A^(−m) ishydroxide.

Representative examples of suitable phase transfer catalysts include,but are not limited to, tetramethylammonium chloride,tetramethylammonium bromide, tetramethylammonium iodide,tetramethylammonium hydroxide, tetraethylammonium chloride,tetraethylammonium bromide, tetraethylammonium iodide,tetraethylammonium hydroxide, tetrabutylammonium chloride,tetrabutylammonium bromide, tetrabutylammonium iodide,tetrabutylammonium hydroxide, methyltributylammonium chloride,methyltributylammonium bromide, methyltributylammonium iodide,methyltributylammonium hydroxide, tetraoctylammonium chloride,tetraoctylammonium bromide, tetraoctylammonium iodide,tetraoctylammonium hydroxide, methyltrioctylammonium chloride,methyltrioctylammonium bromide, methyltrioctylammonium iodide,methyltrioctylammonium hydroxide, benzyltrimethylammonium chloride,benzyltrimethylammonium bromide, benzyltriethylammonium chloride,benzyltributylammonium chloride, dibenzyldimethylammonium chloride,dibenzyldiimethylammonium bromide, dibenzyldiethylammonium chloride,dibenzyldibutylammonium chloride, and the like and aqueous solutionsthereof.

In one embodiment, the phase transfer catalysts are aqueous solutions oftetraethylammonium chloride, tetrabutylammonium chloride,tetrabutylammonium bromide, tetrabutylammonium hydroxide,methyltributylammonium chloride, tetraoctylammonium chloride,tetraoctylammonium bromide, methyltrioctylammonium chloride,methyltrioctylammonium bromide, methyltrioctylammonium iodide,methyltrioctylammonium hydroxide, benzyltrimethylammonium chloride,benzyltriethylammonium chloride, benzyltributylammonium chloride,dibenzyldiethylammonium chloride, and dibenzyldibutylammonium chloride.

In another embodiment, the phase transfer catalysts are aqueoussolutions of tetraethylammonium chloride, tetrabutylammonium chloride,tetrabutylammonium bromide, tetrabutylammonium hydroxide,methyltributylammonium chloride, tetraoctylammonium chloride,methyltrioctylammonium chloride, methyltrioctylammonium bromide,methyltrioctylammonium hydroxide, benzyltriethylammonium chloride,benzyltributylammonium chloride, and dibenzyldibutylammonium chloride.

The phase transfer catalyst can be added at any point during thereaction, either all at once, in two or more doses, or in a continuousor semi-continuous manner, or as any combination thereof. A single phasetransfer catalyst may be used, or a combination of several, added as ablend, as individual components, or any combination thereof. Differentcatalysts may optionally be added at different points along the entirereaction sequence. The phase transfer catalyst(s) may be added only inthe first step, in which aqueous sulfide and/or hydrosulfide is reactedwith the acid halide; or only in the second step, in which the aqueousthiocarboxylate is reacted with the haloalkyl silane. Alternatively, thephase transfer catalyst(s) may be added in both steps at the same ordifferent levels.

As one skilled in the art will readily appreciate, the quantity of phasetransfer catalyst to be used depends on the desired rate of reaction andthe level of side products that can be tolerated, among other factors.Alternative, the reactions can be run without a phase transfer catalyst.However, if a phase transfer catalyst is used, appropriateconcentrations to be used during the reactions can range from aconcentration of about 1 ppm (part per million, by weight) to about 3percent by weight and all subranges therebetween. In one embodiment,concentrations of the phase transfer catalyst can range from about 10ppm to about 1 weight percent and all subranges therebetween. In anotherembodiment, the concentrations of the phase transfer catalyst can rangefrom about 50 ppm to about 0.5 weight percent and all subrangestherebetween. Quantities below about 1 ppm of phase transfer catalystcan also be used, but this will give results similar to that obtainedwithout the use of a phase transfer catalyst.

Preparation of Cyclic and Bridging Dialkoxy Blocked MercaptofunctionalSilanes Transesterification Method for Thiocarboxylate Silanes

The preparation of the cyclic and bridging dialkoxy blockedmercaptofunctional silanes generally involves at least atransesterification reaction between a neat thiocarboxylate-alkoxysilane and a diol. The reaction may be carried out by catalyzing amixture of thiocarboxylate-alkoxy silane and a diol at a molar ratio ofabout 0.5 moles of diol per alkoxy-silyl group to be transesterified orcam range from about 0.5 to about 1.5 for a trialkoxy silane. In oneembodiment, the ratio can range from about 1.0 to about 1.5 for atrialkoxy silane. The reaction can be carried out at a temperatureranging from about 10 to about 150° C. and all subranges therebetweenwhile maintaining a pressure in the range of 0.1 to 2000 mm Hg absolute.In one embodiment, the temperature can range from about 30° C. to about90° C. and all subranges therebetween. In another embodiment, thepressure can range from about 1 to about 80 mm Hg absolute. As thoseskilled in the art will recognize, excess diol could be utilized toincrease reaction rate, but it is not necessary under these conditionsas it increases the cost. The reaction may be carried out by slowlyadding diol to catalyzed thiocarboxylate silane at the desired reactiontemperature and vacuum. In this manner, the reaction has betterselectivity, is better controlled, and has a shorter reaction anddistillation cycle. If desired, a neutralization step may be utilized toneutralize an acid or base catalyst and improve product storage.Stripping of residual alcohol following neutralization may be conductedin a batch mode or can be run in continuous distillation equipment.

The thiocarboxylate silane transesterification advantageously proceedswithout degradation or substitution of the thiol group. Additionally,the products of the transesterification of thiocarboxylate silane cancomprise a considerable fraction of monomeric material with secondaryformation of dimers and other low molecular weight cyclic and bridgedoligomers as illustrated by low viscosity reaction products. Also, resinor gel formation can be substantially reduced or not present at all.

Optionally, an inert solvent may be used in the process. The solvent mayserve as a diluent, carrier, stabilizer, refluxing aid, or heatingagent. Generally any inert solvent which does not enter into thereaction or adversely affect the reaction may be used. In oneembodiment, the solvents are those which are liquid under normalconditions and have a boiling point below about 150° C. Examples includearomatic, hydrocarbon, ether, aprotic, or chlorinated hydrocarbonsolvents such as toluene, xylene, hexane, butane, diethyl ether,dimethylformamide, dimethyl sulfoxide, carbon tetrachloride, methylenechloride, and the like.

Alternatively, the transesterification process may be conductedcontinuously. In this case the process comprises:

-   -   a) reacting, in a thin film reactor, a thin film reaction medium        comprising an organofunctional silane, e.g., a thiocarboxylate        silane, a diol and a catalyst to provide diol-derived        organofunctional silanes and by-product alcohol;    -   b) vaporizing the by-product alcohol from the thin film to drive        the reaction;    -   c) recovering the diol-derived organofunctional silane reaction        product;    -   d) optionally, recovering the by-product alcohol by        condensation; and,    -   e) optionally, neutralizing the diol-derived organofunctional        silane product to improve its storage stability.

The molar ratio of diol to thiocarboxylate silane used in the continuousthin film process will depend upon the number of alkoxy groups that aredesired to be replaced with a diol group. Theoretically, a molar ratioof about 0.5 moles of diol is required per alkoxy-silyl group to betransesterified. For a trialkoxy silane, the stoichiometric equivalentmolar ratio is about 1, wherein one diol replaces two alkoxy groups.Generally, the necessary molar ratio operates close to theoretical. Themolar ratio of diol to thiocarboxylate silane can vary, e.g., within arange of about 95 to about 125 percent and all subranges therebetween ofstoichiometric equivalence for each alkoxy-silyl group to betransesterified. In one embodiment, the molar ratio of diol tothiocarboxylate silane can range from about 100 to about 110 percent ofstoichiometric equivalence and all subranges therebetween. In anotherembodiment, a range of about 100 to about 105 percent of stoichiometricequivalence and all subranges therebetween for the molar ratio of diolto thiocarboxylate can be used. As one skilled in the art will readilyrecognize, excess diol can be utilized to increase reaction rates, butit is not necessary when conducting the reaction in a thin film and itis not economical.

The method of forming the film can be any of those known in the art.Typical known devices include but are not limited to, falling film orwiped film evaporators. Minimum film thickness and flow rates willdepend on the minimum wetting rate for the film forming surface. Maximumfilm thickness and flow rates will depend on the flooding point for thefilm and device. Vaporization of the alcohol from the film is effectedby heating the film, by reducing pressure over the film, or by acombination of both. In one embodiment, mild heating and reducedpressure are utilized to form the structures of this invention. Optimaltemperatures and pressures (partial vacuum) for running this processwill depend upon the specific thiocarboxylate silane's alkoxy groups andthe diol or dialcoholamine used in the process. Additionally if anoptional inert solvent is used in the process, that choice will affectthe optimal temperatures and pressures (partial vacuum) utilized.Examples of such solvents include those listed above.

The byproduct alcohol vaporized from the film is removed from thereactive distillation device by a standard partial vacuum-forming deviceand can be condensed, collected, and recycled as feed to otherprocesses. The silane product is recovered by standard means from thereactive distillation device as a liquid phase. If an inert solvent hasbeen used or if additional purification is necessary, the silane productmay be fed to another similar distillation device or distillation columnto effect that separation. Optionally the product may be neutralized toimprove product storage.

Utility of Cyclic and Bridging Dialkoxy Blocked MercaptofunctionalSilanes

The cyclic and bridging dialkoxy blocked mercaptofunctional silanecompositions described herein are useful as coupling agents betweenorganic polymers (i.e. rubbers) and inorganic fillers. The cyclic andbridging dialkoxy blocked mercaptofunctional silanes are unique in thatthe high efficiency of the mercapto group can be utilized without thedetrimental side effects typically associated with the use ofmercaptosilanes such as, for example, high processing viscosity, lessthan desirable filler dispersion, premature curing (scorch), and odor.These benefits are obtained because the mercaptan group initially isnon-reactive because of the blocking group. The blocking groupsubstantially prevents the silane from coupling to the organic polymerduring the compounding of the rubber. Generally, only the reaction ofthe alkoxysilane group with the filler can occur at this stage of thecompounding process. Thus, substantial coupling of the filler to thepolymer is precluded during mixing, thereby minimizing the undesirablepremature curing (scorch) and the associated undesirable increase inviscosity. One can achieve better cured filled rubber properties suchas, for example, a balance of high modulus and abrasion resistance,because of the avoidance of premature curing.

The cyclic and bridging dialkoxy blocked mercaptofunctional silanecoupling agents herein provide significant advantages over traditionalcoupling agents that have found extensive use in the known art. Theseall comprise in their molecular structures three ethoxy groups on eachsilicon atom, which results in the release of up to three moles ofethanol for each silane equivalent during the rubber manufacturingprocess in which the silane silicon couples to the filler. The releaseof this ethanol is a great disadvantage because it is flammable andtherefore poses a threat of fire, and because it contributes so greatlyto volatile organic compound (VOC) emissions and is thereforepotentially harmful to the environment. The cyclic and bridging dialkoxyblocked mercaptofunctional silane coupling agent compositions describedherein eliminate or greatly mitigate this problem by capping the ethanolemissions to only one, less than one, or even essentially zero moles ofethanol per silane equivalent. They accomplish this because the silaneethoxy groups are replaced with diol-derived alkoxy groups and thusdiols are released during the rubber manufacture process in place ofmuch, or nearly all, of the ethanol released. The diols, having boilingpoints well in excess of rubber processing temperatures, are notvaporized out of the rubber during the rubber manufacture process, as isthe ethanol, but are retained by the rubber where they migrate to thesilica surface due to their high polarity and become hydrogen bonded tothe also polar silica surface. The presence of the diols on the silicasurface then leads to further advantages not obtainable with ethanol(due to its volatility and ejection during the rubber compoundingprocess) in the subsequent cure process, in which such presence preventsthe silica surface from binding the curatives and thereby interferingwith the cure. Traditional silanes not based on diols require morecuratives to counter losses due to silica binding.

The addition of hydrocarbon-based diols to the rubber compoundingformulation prior to and/or concurrent with the addition of curatives isof advantage for the efficient utilization of the curatives, inparticular, and polar substances, such as (but not limited to) amines,amides, sulfenamides, thiurams, and guanidines. Whether diols areexclusively added in the form of diol-derived silanes or as free diolsin combination with the silane coupling agents, the polarity of thediols is of advantage to the rubber compounding process. These polarsubstances tend to migrate to the filler surface due to dipoleinteractions with the filler. This tends to make them unavailable fortheir intended function within the organic polymer matrix, where theirfunctions include such things as vulcanization and/or couplinginitiatiation, acceleration, retardation, or sulfur atom transfer and/oractivation. The hydrocarbon-based diols enhance the function of thecuratives by interfering with their tendency to bind to the silicasurface, thereby forcing them into the rubber matrix to perform theirfunction. The hydrocarbon-based diols accomplish this by themselvesbeing very polar, and thereby by themselves binding to the fillersurface, leaving less room for the curatives to bind to filler. Thehydrocarbon based diols thus act as curative displacing agents from thefiller.

The short chain of the hydrocarbon-based diols can further enhance theirfunction by a chelate effect. Chains of two or three carbon atomsbetween the two OH groups of the diol promote the formation of 5- or6-membered rings when both oxygen atoms bind to a common atom, such as aproton residing on the filler. This dual binding to a common center,known as, and referred to herein as, the chelate effect, enhances theaffinity of the diol to the filler and thereby enhances its ability toprevent the binding of the curatives to the filler.

The hydrocarbon-based diols used herein are superior to ether- and/orpolyether-based monofunctional alcohols or difunctional alcohols (diols)because the lack of the ether functionality of the hydrocarbon baseddiols avoids the problems typically encountered with ethers. Theseproblems include high toxicity, their tendency for spontaneous peroxideformation, and high chain lengths between OH groups. Spontaneousperoxide formation is a problem because it is difficult to prevent andbecause the peroxides lead to flammability hazards. Furthermore, theperoxides decompose when heated to free radicals, which can initiateunwanted side reactions in the rubber polymers. These side reactionsinclude peroxide-induced cure chemistries, in which polymer chains arecrosslinked. This can lead to premature, excess, and variablecrosslinking during or prior to cure. The excess crosslinking can leadto inferior properties in the rubber, premature crosslinking can lead toscorch, and the variability makes it hard to fabricate a reproduciblerubber composition and any articles of manufacture derived thereof.

The excess chain lengths of the ether-comprising diols forces chelationby the two OH groups to involve ring sizes of at least about 8 atoms,which is well beyond the optimum 5 or 6, accessible to hydrocarbon baseddiols. Chelation involving an OH group and an ether, which would givethe optimum 5 or 6 membered rings, is not as strong as chelation withthe two OH groups accessible to the hydrocarbon based diols because theOH groups are less sterically hindered and because the OH groups aremore active at forming hydrogen bond interactions, which are key tobinding the diols to the filler surface.

The silanes used herein are advantageously designed so that thebyproducts of the silane coupling process are themselves of utility inenhancing the rubber compounding process, the value of the derivedrubber composition, and/or any articles of manufacture derived from therubber composition. Thus, 1) the sulfur portion of the coupling agentcomprises a blocking group which not only retards coupling of silane topolymer during mixing, activating the sulfur only during the cure, butthe blocking group also functions by compatibilizing the filler with thepolymer during mixing through the hydrophobic interactions with thepolymer, thereby enhancing the ease and completeness filler dispersionand retarding the reversal of this process, namely fillerreagglomeration (Payne Effect); and 2) the diols released from thesilane silicon during the process of coupling to the filler are not justshed as a waste product, but perform an important follow-up function.This function relates to enhancing the efficiency of the curatives,which was described above.

In use, at least one of the cyclic and bridging dialkoxy blockedmercaptofunctional silane compositions of the present invention is mixedwith the organic polymer before, during, or after the compounding of thefiller into the organic polymer. It is advantageous to add the silanesbefore or during the compounding of the filler into the organic polymerbecause these silanes facilitate and improve the dispersion of thefiller. The total amount of the silane composition present in theresulting combination can range from about 0.05 to about 25 parts byweight per hundred parts by weight of organic polymer (phr) and allsubranges therebetween. In another embodiment, the total amount ofsilane present in the resulting combination can range from about 1 toabout 10 phr and all subranges therebetween. Fillers can be used inquantities ranging from about 5 to about 100 phr and all subrangestherebetween. In another embodiment, the filler can be used in an amountranging from about 25 to about 80 phr and all subranges therebetween.

When reaction of the mixture to couple the filler to the polymer isdesired, a deblocking agent is added to the mixture to deblock thecyclic and bridging dialkoxy blocked mercaptofunctional silanes. Thedeblocking agent may be added at quantities ranging from about 0.1 toabout 5 phr and all subranges therebetween. In another embodiment, thedeblocking agent can be used in an amount ranging from about 0.5 toabout 3 phr and all subranges therebetween. If alcohol or water arepresent in the mixture (as is common), a catalyst (e.g., tertiaryamines, Lewis acids, or thiols) may be used to initiate and promote theloss of the blocking group by hydrolysis or alcoholysis to liberate thecorresponding mercaptosilane. Alternatively, the deblocking agent may bea nucleophile comprising a hydrogen atom sufficiently labile such thathydrogen atom could be transferred to the site of the original blockinggroup to form the mercaptosilane. Thus, with a blocking group acceptormolecule, an exchange of hydrogen from the nucleophile would occur withthe blocking group of the blocked mercaptosilane to form themercaptosilane and the corresponding derivative of the nucleophilecomprising the original blocking group. This transfer of the blockinggroup from the silane to the nucleophile could be driven by, forexample, a greater thermodynamic stability of the products(mercaptosilane and nucleophile comprising the blocking group) relativeto the initial reactants (cyclic and bridging dialkoxy blockedmercaptofunctional silanes and nucleophile). For example, if thenucleophile were an amine comprising an N—H bond, transfer of theblocking group from the cyclic and bridging dialkoxy blockedmercaptofunctional silane would yield the mercaptosilane and one ofseveral classes of amides corresponding to the type of blocking groupused. For example, carboxyl blocking groups deblocked by amines wouldyield amides, sulfonyl blocking groups deblocked by amines would yieldsulfonamides, sulfinyl blocking groups deblocked by amines would yieldsulfinamides, phosphonyl blocking groups deblocked by amines would yieldphosphonamides, and phosphinyl blocking groups deblocked by amines wouldyield phosphinamides. What is important is that regardless of theblocking group initially present on the cyclic and bridging dialkoxyblocked mercaptofunctional silane and regardless of the deblocking agentused, the initially substantially inactive (from the standpoint ofcoupling to the organic polymer) cyclic and bridging dialkoxy blockedmercaptofunctional silane is substantially converted at the desiredpoint in the rubber compounding procedure to the active mercaptosilane.It is noted that partial amounts of the nucleophile may be used (i.e., astoichiometric deficiency), if one were to only deblock part of thecyclic and bridging dialkoxy blocked mercaptofunctional silanecomposition to control the degree of vulcanization of a specificformulation.

Water typically is present on the inorganic filler as a hydrate or boundto a filler in the form of a hydroxyl group. The deblocking agent can beadded in the curative package or, alternatively, at any other stage inthe compounding process as a single component. Examples of nucleophileswould include any primary or secondary amines, or amines comprising C═Ndouble bonds, e.g., imines, guanidines and the like; with the provisothat the amine comprises at least one N—H (nitrogen-hydrogen) bond.Numerous examples of guanidines, amines, and imines well known in theart, which are useful as components in curatives for rubber, are citedin Rubber Chemicals; J. Van Alphen; Plastics and Rubber ResearchInstitute TNO, Delft. Holland; 1973. Representative examples include,but are not limited to, N,N′-diphenylguanidine,N,N′,N″-triphenylguanidine, N,N′-di-ortho-tolylguanidine,ortho-biguanide, hexamethylenetetramine, cyclohexylethylamine,dibutylamine, 4,4′-diaminodiphenylmethane and the like. Any general acidcatalysts used to transesterify esters, such as Bronsted or Lewis acids,could be used as catalysts.

The rubber composition need not be, but usually is, substantially freeof functionalized siloxanes, especially those of the type disclosed inAustralian Patent AU-A-10082/97, which is incorporated herein byreference. In one embodiment, the rubber composition is free offunctionalized siloxanes.

In practice, sulfur vulcanized rubber products typically are prepared bythermomechanically mixing rubber and various ingredients in asequentially step-wise manner followed by shaping and curing thecompounded rubber to form a vulcanized product. First, for the aforesaidmixing of the rubber and various ingredients, typically exclusive ofsulfur and sulfur vulcanization accelerators (collectively “curingagents”), the rubber(s) and various rubber compounding ingredients areusually blended in at least one, and often (in the case of silica filledlow rolling resistance tires) two, preparatory thermomechanical mixingstage(s) in suitable mixers. Such preparatory mixing is referred to asnon-productive mixing or non-productive mixing steps or stages. Suchpreparatory mixing usually is conducted at temperatures in the range offrom about 140° C. to about 20° C. and all subranges therebetween andoften in the range of from about 150° C. to about 180° C. and allsubranges therebetween.

Subsequent to such preparatory mix stages, in a final mixing stage,sometimes referred to as a productive mix stage, deblocking agent (inthe case of this invention), curing agents, and possibly one or moreadditional ingredients, are mixed with the rubber compound orcomposition, typically at a temperature in a range of about 50° C. toabout 130° C., which is a lower temperature than those utilized in thepreparatory mix stages to prevent or retard premature curing of thesulfur curable rubber, which is sometimes referred to as scorching ofthe rubber composition.

The rubber mixture, sometimes referred to as a rubber compound orcomposition, typically is allowed to cool, sometimes after or during aprocess intermediate mill mixing, between the aforesaid various mixingsteps, for example, to a temperature of about 50° C. or lower.

When it is desired to mold and to cure the rubber, the rubber is placedinto the appropriate mold at about at least about 130° C. and up toabout 200° C., which will cause the vulcanization of the rubber by themercapto groups on the mercaptosilane and any other free sulfur sourcesin the rubber mixture.

By thermomechanical mixing, it is meant that the rubber compound, orcomposition of rubber and rubber compounding ingredients, is mixed in arubber mixture under high shear conditions where it autogenously heatsup as a result of the mixing, primarily due to shear and associatedfriction within the rubber mixture in the rubber mixer. Several chemicalreactions may occur at various steps in the mixing and curing processes.

The first reaction is a relatively fast reaction and is consideredherein to take place between the filler and the alkoxysilane group ofthe cyclic and bridging dialkoxy blocked mercaptofunctional silanes.Such reaction may occur at a relatively low temperature, such as, forexample, about 120° C. The second and third reactions are consideredherein to be the deblocking of the cyclic and bridging dialkoxy blockedmercaptofunctional silanes and the reaction which takes place betweenthe sulfur portion of the organosilane (after deblocking), and thesulfur vulcanizable rubber at a higher temperature: for example, aboveabout 140° C.

Another sulfur source may be used, for example, in the form of elementalsulfur as S_(g). A sulfur donor is considered herein as asulfur-containing compound that liberates free, or elemental sulfur, ata temperature in a range of about 140° C. to about 190° C. Such sulfurdonors may be, for example, although are not limited to, polysulfidevulcanization accelerators and organosilane polysulfides with at leasttwo connecting sulfur atoms in their polysulfide bridge. The amount offree sulfur source addition to the mixture can be controlled ormanipulated as a matter of choice relatively independently from theaddition of the aforesaid cyclic and bridging dialkoxy blockedmercaptofunctional silane composition.

Thus, for example, the independent addition of a sulfur source may bemanipulated by the amount of addition thereof and by sequence ofaddition relative to addition of other ingredients to the rubbermixture.

Addition of an alkyl silane to the coupling agent system (cyclic andbridging dialkoxy blocked mercaptofunctional silane plus additional freesulfur source and/or vulcanization accelerator) typically in a moleratio range of alkyl silane to cyclic and bridging dialkoxy blockedmercaptofunctional silane of about 1/50 to about ½ promotes an evenbetter control of rubber composition processing and aging.

A rubber composition is prepared by a process comprising the sequentialsteps of:

-   -   a) thermomechanically mixing, in at least one preparatory mixing        step, under effective mixing conditions, e.g., at a temperature        from about 120° C. to about 200° C. and all subranges        therebetween in a first embodiment and from about 140° C. to        about 190° C. and all subranges therebetween in a second        embodiment, for a total mixing time of from about 2 to about 20        minutes and all subranges therebetween in a first embodiment and        from about 4 to about 15 minutes and all subranges therebetween        in a second embodiment for such mixing step(s):        -   i) about 100 parts by weight of at least one sulfur            vulcanizable rubber selected from conjugated diene            homopolymers and copolymers, and copolymers of at least one            conjugated diene and aromatic vinyl compound,        -   ii) from about 5 to about 100 phr and all subranges            therebetween of a particulate filler in a first embodiment            and from about 25 to about 80 phr and all subranges            therebetween of a particulate filler in a second embodiment,            wherein the particulate filler can comprise from about 1 to            about 85 weight percent and all subranges therebetween            carbon black, and        -   iii) from about 0.05 to about 20 parts by weight of            filler (ii) and all subranges therebetween of at least one            cyclic and bridging dialkoxy organofunctional silane            composition; and, optionally,    -   b) subsequently blending therewith, in a final thermomechanical        mixing step under effective blending conditions, e.g., at a        temperature of from about 50° C. to about 130° C. for a time        sufficient to blend the rubber, e.g., from about 1 to about 30        minutes in a first embodiment and from about 1 to about 3        minutes in a second embodiment, at least one deblocking agent at        about 0.05 to about 20 parts by weight of the filler and all        subranges therebetween and at least one curing agent at 0 to        about 5 phr and all subranges therebetween; and, optionally,    -   c) curing the mixture under effective curing conditions, e.g.,        at a temperature of from about 130° C. to about 200° C. and all        subranges therebetween for a period of from about 5 to about 60        minutes and all subranges therebetween.

The process may also comprise the additional steps of preparing anassembly of a tire or sulfur vulcanizable rubber with a tread comprisedof the rubber composition prepared according to this invention andvulcanizing the assembly at a temperature in a range of about 130° C. toabout 200° C. and all subranges therebetween.

Suitable organic polymers and fillers for use herein are well known inthe art and are described in numerous texts, of which two examplesinclude The Vanderbilt Rubber Handbook; R. F. Ohm, ed.; R.T. VanderbiltCompany, Inc., Norwalk, Conn.; 1990 and Manual For The Rubber Industry;T. Kempermann, S. Koch, J. Sumner, eds.; Bayer AG, Leverkusen, Germany;1993. Representative examples of suitable polymers include solutionstyrene-butadiene rubber (SSBR), styrene-butadiene rubber (SBR), naturalrubber (NR), polybutadiene rubber (BR), ethylene-propylene co- andter-polymers (EP, EPDM), and acrylonitrile-butadiene rubber (NBR).

Generally, the rubber composition can be comprised of at least onediene-based elastomer, or rubber. Suitable conjugated dienes include,but are not limited to, isoprene, 1,3-butadiene and the like andmixtures thereof. Suitable vinyl aromatic compounds include, but are notlimited to, styrene, alpha methyl styrene and the like and mixturesthereof. Thus, the rubber is a sulfur curable rubber. Such diene basedelastomer, or rubber, may be selected, for example, from at least one ofcis-1,4-polyisoprene rubber (natural and/or synthetic), and naturalrubber), emulsion polymerization prepared styrene/butadiene copolymerrubber, organic solution polymerization prepared styrene/butadienerubber, e.g., of from about 10 to about 80 weight percent vinyl contentin one embodiment, from about 25 to about 48 weight percent vinylcontent in a second embodiment and from about 53 to about 75 weightpercent vinyl content in a third embodiment, 3,4-polyisoprene rubber,isoprene/butadiene rubber, styrene/isoprene/butadiene terpolymer rubber,polybutadiene rubber of low cis-1,4 content (i.e., from about 5 to about19 weight percent), medium cis-1,4 content (i.e., from about 20 to about89 weight percent) or high cis-1,4 content (i.e., at least about 90weight percent), and a vinyl content of from 0 to about 50 weightpercent, styrene/isoprene copolymers, emulsion polymerization preparedstyrene/butadiene/acrylonitrile terpolymer rubber andbutadiene/acrylonitrile copolymer rubber. An emulsion polymerizationderived styrene/butadiene (E-SBR) may be used having a relativelyconventional styrene content of from about 20 to about 28 weight percentbound styrene or, for some applications, an E-SBR having a medium torelatively high bound styrene content, namely, a bound styrene contentof from about 30 to about 45 weight percent. Emulsion polymerizationprepared styrene/butadiene/acrylonitrile terpolymer rubbers comprisingfrom 2 to about 40 weight percent bound acrylonitrile in the terpolymerare also contemplated as diene based rubbers for use in this invention.

The solution polymerization prepared SBR (S-SBR) typically has a boundstyrene content of up to about 50 percent in one embodiment and fromabout 5 to about 36 percent in another embodiment.

Representative examples of suitable filler materials include metaloxides, such as silica (pyrogenic and precipitated), titanium dioxide,aluminosilicate, and alumina, siliceous materials, including clays andtalc, and carbon black. Particulate, precipitated silica is alsosometimes used for such purpose, particularly in connection with asilane. In some cases, a combination of silica and carbon black isutilized for reinforcing fillers for various rubber products, includingtreads for tires. Alumina can be used either alone or in combinationwith silica. The term “alumina” can be described herein as aluminumoxide, or Al₂O₃. The fillers may be hydrated or in anhydrous form. Useof alumina in rubber compositions is known, see, for example, U.S. Pat.No. 5,116,886 and EP 631 982.

The cyclic and bridging dialkoxy blocked mercaptofunctional silanecompositions may be premixed, or pre-reacted, with the filler particlesor added to the rubber mix during the rubber and filler processing, ormixing stage. If the silane and filler are added separately to therubber mix during the rubber and filler mixing, or processing stage, itis considered that the cyclic and bridging dialkoxy blockedmercaptofunctional silanes then couple in situ to the filler.

The vulcanized rubber composition should comprise a sufficient amount offiller to contribute a reasonably high modulus and high resistance totear. The combined weight of the filler may be as low as about 5 toabout 100 ph and all subranges therebetween r, but it can be from about25 to about 85 phr and all subranges therebetween in another embodiment.

In one embodiment precipitated silicas are utilized as a filler. Thesilica may be characterized by having a BET surface area, as measuredusing nitrogen gas, in the range of about 40 to about 600, and moreusually in a range of about 50 to about 300 m²/g. The BET method ofmeasuring surface area is described in the Journal of the AmericanChemical Society, Volume 60, page 304 (1930). The silica typically mayalso be characterized by having a dibutylphthalate (DBP) absorptionvalue in a range of about 100 to about 350, and more usually about 150to about 300. Further, the silica, as well as the aforesaid alumina andaluminosilicate, may be expected to have a CTAB surface area in a rangeof about 100 to about 220. The CTAB surface area is the external surfacearea as evaluated by cetyl trimethylammonium bromide with a pH of about9. The method is described in ASTM D 3849.

Mercury porosity surface area is the specific surface area determined bymercury porosimetry. For such technique, mercury is penetrated into thepores of the sample after a thermal treatment to remove volatiles. Setup conditions may be suitably described as using about a 100 mg sample,removing volatiles during about 2 hours at about 105° C. and ambientatmospheric pressure to about 2000 bars pressure measuring range. Suchevaluation may be performed according to the method described inWinslow, Shapiro in ASTM bulletin, p. 39 (1959) or according to DIN66133. For such an evaluation, a CARLO-ERBA Porosimeter 2000 might beused. The average mercury porosity specific surface area for the silicashould be in a range of about 100 to about 300 m²/g.

In one embodiment a suitable pore size distribution for the silica,alumina and aluminosilicate according to such mercury porosityevaluation is considered herein to be five percent or less of its poreshave a diameter of less than about 10 nm; about 60 to about 90 percentof its pores have a diameter of about 10 to about 100 nm; about 10 toabout 30 percent of its pores have a diameter at about 100 to about1,000 nm; and about 5 to about 20 percent of its pores have a diameterof greater than about 1,000 nm.

In a second embodiment the silica may be expected to have an averageultimate particle size, for example, in the range of about 0.01 to about0.05 μm as determined by the electron microscope, although the silicaparticles may be even smaller, or possibly larger, in size. Variouscommercially available silicas may be considered for use in thisinvention such as, from PPG Industries under the HI-SIL trademark withdesignations HI-SIL 210, 243, etc.; silicas available fromRhone-Poulenc, with, for example, designation of ZEOSIL 1165 MP; silicasavailable from Degussa with, for example, designations VN2 and VN3, etc.and silicas commercially available from Huber having, for example, adesignation of HUBERSIL 8745.

Where it is desired for the rubber composition, which comprises both asiliceous filler such as silica, alumina and/or aluminosilicates andalso carbon black reinforcing pigments, to be primarily reinforced withsilica as the reinforcing pigment, the weight ratio of such siliceousfillers to carbon black can be about at least 3/1 in one embodiment,about at least 10/1 in another embodiment and, thus, in a range of about3/1 to about 30/1. The filler may be comprised of about 15 to about 95weight percent precipitated silica; alumina and/or aluminosilicate and,correspondingly about 5 to about 85 weight percent carbon black, whereinthe carbon black has a CTAB value in a range of about 80 to about 150.Alternatively, the filler can be comprised of about 60 to about 95weight percent of the silica and all subranges therebetween, aluminaand/or aluminosilicate and, correspondingly, about 40 to about 5 weightpercent carbon black and all subranges therebetween. The siliceousfiller and carbon black may be pre-blended or blended together in themanufacture of the vulcanized rubber.

The rubber composition may be compounded by methods known in the rubbercompounding art, such as mixing the various sulfur-vulcanizableconstituent rubbers with various commonly used additive materials suchas, for example, curing aids, such as sulfur, activators, retarders andaccelerators, processing additives, such as oils, resins includingtackifying resins, silicas, plasticizers, fillers, pigments, fatty acid,zinc oxide, waxes, antioxidants and antiozonants, peptizing agents, andreinforcing materials such as, for example, carbon black. Depending onthe intended use of the sulfur vulcanizable and sulfur vulcanizedmaterial or rubber, the additives mentioned above are selected andcommonly used in conventional amounts.

The vulcanization may be conducted in the presence of an additionalsulfur vulcanizing agent. Examples of suitable sulfur vulcanizing agentsinclude, for example elemental sulfur (free sulfur) or sulfur donatingvulcanizing agents, for example, an amino disulfide, polymericpolysulfide or sulfur olefin adducts which are conventionally added inthe final, productive, rubber composition mixing step. The sulfurvulcanizing agents, which are common in the art are used, or added inthe productive mixing stage, in an amount ranging from about 0.4 toabout 3 phr and all subranges therebetween, or even, in somecircumstances, up to about 8 phr, with a range of from about 1.5 toabout 2.5 phr and all subranges therebetween in one embodiment and fromabout 2 to about 2.5 phr and all subranges therebetween in anotherembodiment.

Vulcanization accelerators, i.e., additional sulfur donors, may be usedherein. It is appreciated that may include the following examples,benzothiazole, alkyl thiuram disulfide, guanidine derivatives andthiocarbamates. Representative of such accelerators can be, but notlimited to, mercapto benzothiazole, tetramethyl thiuram disulfide,benzothiazole disulfide, diphenylguanidine, zinc dithiocarbamate,alkylphenoldisulfide, zinc butyl xanthate,N-dicyclohexyl-2-benzothiazolesulfenamide,N-cyclohexyl-2-benzothiazolesulfenamide,N-oxydiethylenebenzothiazole-2-sulfenamide, N,N-diphenylthiourea,dithiocarbamylsulfenamide, N,N-diisopropylbenzothiozole-2-sulfenamide,zinc-2-mercaptotoluimidazole, dithiobis(N-methyl piperazine),dithiobis(N-beta-hydroxy ethyl piperazine) and dithiobis(dibenzylamine). Other additional sulfur donors may be, for example, thiuram andmorpholine derivatives. Representative of such donors are, for example,but not limited to, dimorpholine disulfide, dimorpholine tetrasulfide,tetramethyl thiuram tetrasulfide, benzothiazyl-2,N-dithiomorpholide,thioplasts, dipentamethylenethiuram hexasulfide, anddisulfidecaprolactam.

Accelerators are used to control the time and/or temperature requiredfor vulcanization and to improve the properties of the vulcanizate. Inone embodiment, a single accelerator system may be used, i.e., a primaryaccelerator. Conventionally, a primary accelerator(s) is used in totalamounts ranging from about 0.5 to about 4 and all subranges therebetweenin one embodiment, and from about 0.8 to about 1.5 phr and all subrangestherebetween in another embodiment. Combinations of a primary and asecondary accelerator might be used with the secondary accelerator beingused in smaller amounts (of about 0.05 to about 3 phr and all subrangestherebetween) in order to activate and to improve the properties of thevulcanizate. Delayed action accelerators may be used. Vulcanizationretarders might also be used. Suitable types of accelerators are amines,disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides,dithiocarbamates and xanthates. In one embodiment, the primaryaccelerator is a sulfenamide. If a second accelerator is used, thesecondary accelerator can be a guanidine, dithiocarbamate or thiuramcompound.

Typical amounts of tackifier resins, if used, comprise about 0.5 toabout 10 phr and all subranges therebetween, usually about 1 to about 5phr and all subranges therebetween. Typical amounts of processing aidscomprise about 1 to about 50 phr and all subranges therebetween. Suchprocessing aids can include, for example, aromatic, napthenic, and/orparaffinic processing oils. Typical amounts of antioxidants compriseabout 1 to about 5 phr. Representative antioxidants may be, for example,diphenyl-p-phenylenediamine and others, such as, for example, thosedisclosed in the Vanderbilt Rubber Handbook (1978), pages 344-346.Typical amounts of antiozonants, comprise about 1 to about 5 phr and allsubranges therebetween. Typical amounts of fatty acids, if used, whichcan include stearic acid, comprise about 0.5 to about 3 phr and allsubranges therebetween. Typical amounts of zinc oxide comprise about 2to about 5 phr and all subranges therebetween. Typical amounts of waxescomprise about 1 to about 5 phr and all subranges therebetween. Oftenmicrocrystalline waxes are used. Typical amounts of peptizers compriseabout 0.1 to about 1 ph and all subranges therebetween r. Typicalpeptizers may be, for example, pentachlorothiophenol anddibenzamidodiphenyl disulfide.

The rubber compositions of this invention can be used for variouspurposes. For example, it can be used for various tire compounds. Suchtires can be built, shaped, molded and cured by various methods, whichare known and will be readily apparent to those having skill in suchart. One particularly useful application of the rubber compositionsherein is for the manufacture of tire treads. An advantage of tires,tire treads, of other articles of manufacture derived from the rubbercompositions herein is they suffer from less VOC emissions during theirlifetime and use as a result of having been manufactured from a rubbercompound which comprises less residual silane ethoxy groups than dorubber compounds of the known and presently practiced art. This is adirect result of having used dialkoxy-functional silane coupling agentsin their manufacture, which comprise fewer or essentially no ethoxygroups on silicon, relative to the silane coupling agents of thecurrently known and practiced art. The lack or reduction of ethoxysilanegroups in the coupling agents used results in fewer residual ethoxygroups on silicon after the article of manufacture is produced, fromwhich fewer or no ethanol can be released by hydrolysis of the residualethoxysilane groups by exposure of the article of manufacture to waterduring use.

The rubber compositions herein and the articles of manufacture derivablethereof as described herein are novel from those of the known andcommonly practiced art in that both comprise hydrocarbon backbone baseddiols, as defined herein. Typical examples of such species in the rubbercompositions and articles of manufacture described herein include diolssuch as an isomer of propanediol, pentane diol, and such as ethyleneglycol, and propylene glycol. Additional species would include stearatemonoesters and/or diesters of these diols. These species possesspolarities intermediate between those of the rubber polymers and thefiller, thereby helping to stabilize the compositions and articles ofmanufacture from filler reagglomeration and the resulting degradation ofthe properties and performance parameters thereof.

The invention may be better understood by reference to the followingexamples in which the parts and percentages are by weight unlessotherwise indicated.

Example 1 Preparation of 3-(1,2-ethanedialkoxyethoxysilyl)-1-propylthiooctanoate from aqueous sodium hydrosulfide, octanoyl chloride, and3-(1,2-ethanedialkoxyethoxysilyl)-1-propyl chloride

A 20 weight percent aqueous solution of sodium sulfide was prepared bydissolving sodium sulfide (116 grams, 1.48 moles) in the form ofhydrated flakes (193 grams, 60%) into 385 grams of water in a 5-literround-bottomed flask. This solution was then cooled by means of anice-water bath and converted to an aqueous solution of sodiumhydrosulfide (NaSH) by saturating it with an excess of hydrogen sulfideby adding hydrogen sulfide with stirring until no more was absorbed. Adropping funnel was charged with octanoyl chloride (241 grams, 1.48moles). With the temperature of the sodium hydrosulfide solution in the5-liter flask at 9° C. the addition of the octanoyl chloride to the5-liter flask was begun with stirring of the contents of the 5-literflask with a mechanical stirrer, immediately after the addition of 1.7grams of a 10% aqueous solution of methyltrioctylammonium chloride tothe 5-liter flask. The addition of the octanoyl chloride was completedover the course of 1.8 hours with a final temperature of 13° C. Thecontent of the 5-liter flask was kept between 8 and 19° C. during thecourse of the addition. The content of the 5-liter flask was thenallowed to reach ambient temperature and stirring was stopped, yieldinga clear, slightly viscous, one-phase aqueous solution of sodiumthiooctanoate and sodium chloride.

The solution of sodium thiooctanoate was then brought to 21° C. andstirred with a mechanical stirrer throughout the rest of this procedure.To this solution was added, all at once,3-(1,2-ethanedialkoxyethoxysilyl)-1-propyl chloride (250 grams, 1.19moles). Immediately thereafter was added 1.4 grams of a 10% aqueoussolution of methyltrioctylammonium chloride. Over the next 15 to 20minutes, the temperature of the contents of the 5-liter flask wasincreased to 30° C., with continued stirring. The temperature was thenramped up to 84° C. over the next 50 minutes, and maintained for aboutanother 20 to 21 hours with continued stirring. After cooling to ambienttemperature, agitation was stopped, the two phases were allowed toseparate, and the organic phase was separated from the aqueous phase.

Gas chromatography and mass spectrometry (GC and GCMS) revealed aproduct having 80% 3-(1,2-ethanedialkoxyethoxysilyl)-1-propylthiooctanoate with 1% residual3-(1,2-ethanedialkoxyethoxysilyl)-1-propyl chloride (reported puritiesare based on area percent GC responses). This material was then purifiedby flash vacuum distillation yielding a product of 83% purity.

Example 2 Preparation of3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate fromaqueous sodium hydrosulfide, octanoyl chloride, and3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride

A 20 weight percent aqueous solution of sodium sulfide was prepared andconverted to an aqueous solution of sodium thiooctanoate, by a proceduresimilar to the one described in Example 1. A sample of this solution ofsodium thiooctanoate (854 grams, 1.46 moles) was charged into a 3-literflask. To this solution was added3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride (330grams, 1.24 moles). Immediately thereafter was added 1.5 grams of a 10%aqueous solution of methyltrioctylammonium chloride. Over the next 30minutes, the temperature of the contents of the 3-liter flask wasincreased to 35° C., with continued stirring. The temperature was thenramped up to 81° C. over the next 1 to 1.5 hours, and maintained at thattemperature for about another 5 to 6 hours with continued stirring.After cooling to ambient temperature, agitation was stopped, the twophases were allowed to separate, and the organic phase was separatedfrom the aqueous phase.

Gas chromatography and mass spectrometry (GC and GCMS, respectively)revealed a product having 66%3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate with1% 3-chloro-1-propyltriethoxysilane and 8% residual3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride (reportedpurities are based on area percent GC responses). This material was thenpurified by flash vacuum distillation yielding a product of 81% purity.

Example 3 Preparation of3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate fromaqueous sodium hydrosulfide, octanoyl chloride, and3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride

A 20 weight percent aqueous solution of sodium sulfide was prepared andconverted to an aqueous solution of sodium thiooctanoate, by a proceduresimilar to the one described in Example 1. A sample of this solution ofsodium thiooctanoate (1506 grams, 2.74 moles) was charged into a 3-literflask. To this solution was added3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride (441grams, 1.66 moles). Immediately thereafter was added 1.6 grams of a 10%aqueous solution of methyltrioctylammonium chloride. Over the next 15minutes, the temperature of the contents of the 3-liter flask wasincreased to 32° C., with continued stirring. The temperature was thenramped up to 97° C. over the next 40 minutes. The temperature was thenreduced to 80° C. and maintained at that temperature for another 4 hourswith continued stirring. After cooling to ambient temperature, agitationwas stopped, the two phases were allowed to separate, and the organicphase was separated from the aqueous phase.

Gas chromatography and mass spectrometry revealed a product having 70%3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate with6% residual 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylchloride (reported purities are based on area percent GC responses).This material was then purified by vacuum distillation yielding aproduct of 97% purity.

Example 4 Preparation of3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate fromaqueous sodium hydrosulfide, octanoyl chloride, and3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride

A nominal 20 weight percent aqueous solution of sodium sulfide wasprepared by dissolving sodium sulfide (ca. 166 grams, 2.12 moles) in theform of hydrated flakes (276 grams, ca. 60%) into 552 grams of water ina 5-liter round-bottomed flask. This solution was then cooled by meansof an ice-water bath and converted to an aqueous solution of sodiumhydrosulfide (NaSH) by saturating it with an excess of hydrogen sulfideby adding hydrogen sulfide with stirring until no more was absorbed. Adropping funnel was charged with octanoyl chloride (345 grams, 2.12moles). With the temperature of the sodium hydrosulfide solution in the5-liter flask at 9.5° C. the addition of the octanoyl chloride to the5-liter flask was begun with stirring of the contents of the 5-literflask with a mechanical stirrer. No phase transfer catalyst was added.The addition of the octanoyl chloride was completed over the course of 2hours with a final temperature of 14° C. The content of the 5-literflask was kept between 8 and 12° C. during the course of the addition. ApH measurement, using pH paper, revealed that the solution was alkaline.Additional octanoyl chloride was added dropwise (totaling 15 additionalgrams) to the stirred solution until a neutral pH reading was obtained.The content of the 5-liter flask was then allowed to reach ambienttemperature and stirring was stopped, yielding a clear, slightlyviscous, one-phase aqueous solution of sodium thiooctanoate and sodiumchloride.

The solution of sodium thiooctanoate was then brought to 23° C. andstirred with a mechanical stirrer throughout the rest of this procedure.To this solution was added, all at once,3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride (451grams, 1.69 moles). Immediately thereafter was added 1.5 grams of a 10%aqueous solution of methyltrioctylammonium chloride. Over the next 15minutes, the temperature of the contents of the 5-liter flask wasincreased to 36° C. with continued stirring. The temperature was thenramped up to 83° C. over the next 40 minutes, and maintained for aboutanother 4 hours with continued stirring. After cooling to ambienttemperature, agitation was stopped, the two phases were allowed toseparate, and the organic phase was separated from the aqueous phase.

Gas chromatography and mass spectrometry (GC and GCMS) revealed aproduct having 68% 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthiooctanoate and 2.8% 3-octanoylthio-1-propyltriethoxysilane, with 8%residual 3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride(reported purities are based on area percent GC responses). Thismaterial was then purified by flash vacuum distillation yielding aproduct of 78% purity.

Example 5 Preparation of3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate fromaqueous sodium hydrosulfide, octanoyl chloride, and3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride

A 20 weight percent aqueous solution of sodium sulfide was prepared bydissolving sodium sulfide (ca. 428 grams, 5.49 moles) in the form ofhydrated flakes (714 grams, ca. 60%) into 1430 grams of water in a5-liter round-bottomed flask. This solution was then cooled by means ofan ice-water bath and converted to an aqueous solution of sodiumhydrosulfide by saturating it with an excess of hydrogen sulfide byadding hydrogen sulfide with stirring until no more was absorbed. Aportion (163 grams, 0.77 mole) of this sodium hydrosulfide solution wasremoved. A dropping funnel was charged with octanoyl chloride (794grams, 4.88 moles). With the temperature of the sodium hydrosulfidesolution in the 5-liter flask at 9° C., the addition of the octanoylchloride to the 5-liter flask was begun with stirring of the contents ofthe 5-liter flask with a mechanical stirrer. No phase transfer catalystwas added. The addition of the octanoyl chloride was completed over thecourse of 6.3 hours with a final temperature of 10° C. The contents ofthe 5-liter flask was kept between 8 and 10° C. during the course of theaddition. At this point, a pH measurement, using pH paper, revealed thatthe solution was alkaline. Additional octanoyl chloride was addeddropwise (totaling 15 additional grams) to the stirred solution until aneutral pH reading was obtained. The contents of the 5-liter flask wasthen allowed to reach ambient temperature and stirring was stopped,yielding a clear, slightly viscous, one-phase aqueous solution of sodiumthiooctanoate and sodium chloride.

To this solution was added3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride (1134grams, 4.26 moles). Immediately thereafter was added 2.4 grams of a 10%aqueous solution of methyltrioctylammonium chloride. Over the next 45minutes, the temperature of the contents of the 5-liter flask wasincreased to 50° C., with continued stirring. The temperature was thenramped up to 80° C. over the next 45 minutes, and maintained for aboutanother 3.5 hours with continued stirring. After cooling to ambienttemperature, agitation was stopped, the two phases were allowed toseparate, and the organic phase was separated from the aqueous phase.

Gas chromatography and mass spectrometry revealed a product having 65%3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate and2% 3-octanoylthio-1-propyltriethoxysilane, with 10% residual3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl chloride (reportedpurities are based on area percent GC responses). This material was thenpurified by removing volatiles by means of flash vacuum distillation,and subsequently pressure filtered to yield a product of 85% purity.

Example 6 Preparation of 3-neopentanedialkoxyisopropoxysilyl)-1-propylthiooctanoate from aqueous sodium hydrosulfide, octanoyl chloride, and3-(neopentanedialkoxyisopropoxysilyl)-1-propyl chloride

A 20 weight percent aqueous solution of sodium sulfide was prepared andconverted to an aqueous solution of sodium thiooctanoate, by a proceduresimilar to the one described in Example 1. A sample of this solution ofsodium thiooctanoate (518 grams, 0.94 moles) was charged into a 2-literflask. To this solution was added3-(neopentanedialkoxyisopropoxysilyl)-1-propyl chloride (200 grams, 0.75mole). Immediately thereafter was added 1.3 grams of a 10% aqueoussolution of methyltrioctylammonium chloride. Over the next 30 minutes,the temperature of the contents of the 2-liter flask was increased to35° C. with continued stirring. The temperature was then ramped up to82° C. over the next 60 to 90 minutes, and maintained at thattemperature for another 2.5 hours with continued stirring. After coolingto ambient temperature, agitation was stopped, the two phases wereallowed to separate, and the organic phase was separated from theaqueous phase.

Gas chromatography and mass spectrometry revealed a product having 53%3-neopentanedialkoxyisopropoxysilyl)-1-propyl thioctanoate with 1.8% of3-chloro-1-propyltriisopropoxysilane and 8% residual 3-(neopentanedialkoxyisopropoxysilyl)-1-propylchloride (reported purities are basedon area percent GC responses).

Example 7 Preparation of 3-neopentanedialkoxyisopropoxysilyl)-1-propylthiooctanoate from aqueous sodium hydrosulfide, octanoyl chloride, and3-(neopentanedialkoxyisopropoxysilyl-1-propyl chloride

A 20 weight percent aqueous solution of sodium sulfide was prepared andconverted to an aqueous solution of sodium thiooctanoate by a proceduresimilar to the one described in Example 1. A sample of this solution ofsodium thiooctanoate (519.5 grams, 0.94 mole) was charged into a 2-literflask. To this solution was added3-(neopentanedialkoxyisopropoxysilyl-1-propyl chloride (201 grams, 0.75mole) in the form of a 50 weight percent solution (402 grams) intoluene. Immediately thereafter was added 1.5 grams of a 10% aqueoussolution of methyltrioctylammonium chloride. Over the next 25 minutes,the temperature of the contents of the 2-liter flask was increased to33° C., with continued stirring. The temperature was then ramped up to82° C. over the next 60 minutes, and maintained at that temperature foranother 3.5 hours with continued stirring. The temperature was thenreduced to 63° C. and maintained for an additional 1.7 hours withcontinued stirring. After cooling to ambient temperature, agitation wasstopped, the two phases were allowed to separate, and the organic phasewas separated from the aqueous phase. Volatiles were removed by rotaryevaporation to yield a slightly viscous liquid.

Gas chromatography and mass spectrometry revealed a product having 57%3-neopentanedialkoxyisopropoxysilyl)-1-propyl thiooctanoate with 1.4% of3-chloro-1-propyltriisopropoxysilane and 22% residual3-(neopentanedialkoxyisopropoxysilyl-1-propyl chloride (reportedpurities are based on area percent GC responses). This material was thenpurified by flash vacuum distillation yielding a product of 64% purity.

Example 8 Preparation of3-(2-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate andrelated oligomers from 2-methyl-1,3-propanediol andS-[3-(triethoxysilyl)propyl]thiooctanoate

This example illustrates the transesterification conversion of 2 of the3 ethoxy groups in a trialkoxy silane. A 12-liter round bottom flaskequipped with a mechanical agitator, condenser (connected to a vacuumpump), dropping funnel, internal thermometer, and heating mantle, wascharged with 7292 g (20.0 mol) ofS-[3-(triethoxysilyl)propyl]thiooctanoate and heated to 45° C. 4.55 gSulfuric acid was added and the mixture was stirred well. The pressurein the reaction flask was reduced to 45 mm Hg and 1802 g (20 mol)2-methyl-1,3-propanediol were added from the dropping funnel over 4 hrs.The mixture was maintained at 44 to 45° C. and 45 mm Hg until reactioncompletion. Ethanol formed during the diol addition was continuouslyremoved from the reaction flask, condensed, and collected. Sodiumethylate (11.84 g, 21% solution in ethanol) was added to the flask toneutralize the acid catalyst, and the product was cooled to roomtemperature. The precipitated salts were removed by filtration to yield6956 g of product. Quantitative gas chromatography analysis showed 2.52%unreacted S-[3-(triethoxysilyl)propyl]thiooctanoate. Product gelpermeation chromatography analysis showed Mn=770 and Mw=1500. No gel wasfound in the product.

Example 9 Preparation of3-(2-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate andrelated oligomers from 2-methyl-1,3-propanediol andS-[3-(triethoxysilyl)propyl]thiooctanoate

This example illustrates the transesterification conversion of between 2and 3 of the ethoxy groups. A 5-liter round bottom flask equipped with amechanical agitator, condenser (connected to a vacuum pump), droppingfunnel, internal thermometer, and heating mantle, was charged with 2916g (8.0 mol) of S-[3-(triethoxysilyl)propyl]thiooctanoate and heated to45° C. 1.9 g Sulfuric acid was added and the mixture was stirred well.The pressure in the reaction flask was reduced to 35 mm Hg and 865.5 g(9.6 mol) 2-methyl-1,3-propanediol were added from the dropping funnelover 4 hrs. The mixture was maintained at 44 to 45° C. and 35 mm Hguntil reaction completion. Ethanol (844 g) formed during the dioladdition was continuously removed from the reaction flask, condensed,and collected. Sodium ethylate (4.3 g, 21% solution in ethanol) wasadded to the flask to neutralize the acid catalyst, and the product wascooled to room temperature. The precipitated salts were removed byfiltration to yield 2800.8 g of product. Quantitative gas chromatographyanalysis showed 0.6% unreactedS-[3-(triethoxysilyl)propyl]thiooctanoate. Gel permeation chromatographyanalysis showed Mn=940 and Mw=1940. No gel was found in the product.

Example 10 Preparation of3-(2-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate andrelated oligomers from 2-methyl-1,3-propanediol andS-[3-(triethoxysilyl)propyl]thiooctanoate

This example illustrates the transesterification conversion ofapproximately 3 of the 3 ethoxy groups. A 5-liter round bottom flaskequipped with a mechanical agitator, condenser (connected to a vacuumpump), dropping funnel, internal thermometer, and heating mantle, wascharged with 2916 g (8.0 mol) ofS-[3-(triethoxysilyl)propyl]thiooctanoate and heated to 45° C. 1.9 gSulfuric acid was added and the mixture was stirred well. The pressurein the reaction flask was reduced to 34 mm Hg and 1023.7 g (11.36 mol)2-methyl-1,3-propanediol were added from the dropping funnel over 4 hrs.The mixture was maintained at 44 to 45° C. and 8-13 mm Hg until reactioncompletion. Ethanol (997 g) formed during the diol addition wascontinuously removed from the reaction flask, condensed, and collected.Sodium ethylate (4.15 g, 21% solution in ethanol) was added to the flaskto neutralize the acid catalyst, and the product was cooled to roomtemperature. The precipitated salts were removed by filtration to yield2804.3 g of product. Gel permeation chromatography analysis showedM_(n)=1100 and M_(w)=2280. No gel was found in the product.

Example 11 Preparation of3-(1-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate andRelated Oligomers from 1,3-butanediol andS-[3-(triethoxysilyl)propyl]thiooctanoate

This example illustrates the use of a hindered diol for thetransesterification reaction. A 1-liter round bottom flask equipped witha mechanical agitator, condenser (connected to a vacuum pump), droppingfunnel, internal thermometer, and heating mantle, was charged with 365.7g (1.0 mol) of S-[3-(triethoxysilyl)propyl]thiooctanoate, 91.3 g (1.0mol) 1,3-butanediol, and 0.23 g p-toluenesulfonic acid. The mixture wasstirred vigorously at 45° C. and 45 mm Hg vacuum until the reaction wascompleted, as indicated by GC analysis. Ethanol formed during the dioladdition was continuously removed from the reaction flask, condensed,and collected. Sodium carbonate (0.5 g) was added to the flask, and thereaction mixture was stirred overnight at room temperature to neutralizethe acid catalyst. The precipitated salts were removed by filtration toyield 328.4 g of product. Gas chromatography analysis showed 17.5%unreacted S-[3-(triethoxysilyl)propyl]thiooctanoate and 76.9%3-(1-Methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate. No gelwas found in the product.

Example 12 Preparation of3-(2-methyl-2,4-pentanedioxyethoxysilyl)-1-propyl thiooctanoate andRelated Oligomers from 2-methyl-2,4-pentanediol andS-[3-(triethoxysilyl)propyl]thiooctanoate

This example illustrates the use of a more hindered diol for thetransesterification reaction. A 2-Liter round bottom flask equipped witha mechanical agitator, condenser (connected to a vacuum pump), droppingfunnel, internal thermometer, and heating mantle, was charged with1093.8 g (3.0 mol) of S-[3-(triethoxysilyl)propyl]thiooctanoate, 354.5 g(3.0 mol) 2-methyl-2,4-pentanediol, and 0.9 g p-toluenesulfonic acid.The mixture was stirred vigorously at 40° C. and 38 to 45 mm Hg vacuumuntil the reaction was completed, as indicated by GC analysis. Ethanolformed during the diol addition was continuously removed from thereaction flask, condensed, and collected. Sodium carbonate (5.0 g) wasadded to the flask, and the reaction mixture was stirred overnight atroom temperature to neutralize the acid catalyst. The precipitated saltswere removed by filtration to yield 1016.8 g of product. Gaschromatography analysis showed 16.1% unreactedS-[3-(triethoxysilyl)propyl]thiooctanoate and 64.8%3-(2-Methyl-2,4-pentanedioxyethoxysilyl)-1-propyl thiooctanoate. No gelwas found in the product.

Example 13 Preparation of 3-(1,2-ethanedioxyethoxysilyl)-1-propylthiooctanoate and Related Oligomers from 1,2-ethyleneglycol andS-[3-(triethoxysilyl)propyl]thiooctanoate

This example illustrates the use of a 1,2 diol with no steric hindrancefor the transesterification reaction. A 2-liter round bottom flaskequipped with a mechanical agitator, condenser (connected to a vacuumpump), dropping funnel, internal thermometer, and heating mantle, wascharged with 1093.8 g (3.0 mol) ofS-[3-(triethoxysilyl)propyl]thiooctanoate, 167.6 g (2.7 mol)1,2-ethyleneglycol, and 0.5 g p-toluenesulfonic acid. The mixture wasstirred vigorously at 42° C. and 31 mm Hg vacuum until the reaction wascompleted, as indicated by GC analysis. Ethanol formed during the dioladdition was continuously removed from the reaction flask, condensed,and collected. Sodium carbonate (6.0 g) was added to the flask, and thereaction mixture was stirred overnight at room temperature to neutralizethe acid catalyst. The precipitated salts were removed by filtration toyield 1002.2 g of product. No gel was found in the product.

Example 14 Preparation of3-(2-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate andrelated oligomers from 2-methyl-1,3-propanediol andS-[3-(triethoxysilyl)propyl]thiooctanoate, in a wiped film reactor

This example illustrates a continuous transesterification process forproducing the composition of this invention. The wiped film reactorconsisted of a vertically positioned glass tube, 5.1 cm inside diameterand 38 cm length, fitted with a water-cooled internal condenser, 15 cmlength. Three rotating teflon wiper blades, 20 cm in length, werepositioned 10 cm below the top of the reactor and coupled to a variablespeed control with forward and reverse rotation option. The wiper bladeswere held against the inner walls of the reactor by centrifugal action.The reactor temperature was controlled by means of two electricalheating jackets, wrapped around the outside walls of the reactor.Thermocouples for temperature measurement were placed in the spacebetween the outer wall of the reactor and the heating mantle. The top ofthe reactor was connected to a dry ice condenser fitted with acollection flask, a pressure gauge and a vacuum pump. The reactor feedsystem consisted of two liquid metering piston pumps which co-fedS-[3-(triethoxysilyl)propyl]thiooctanoate and sulfuric acid having2-methyl-1,3-propanol respectively to an in-line static mixer (22 cmlength, 0.64 cm inner diameter). The reactant mixture was dischargedinto the reactor through a port situated 2.5 cm above the wiper blades.During the run, ethanol vapor produced was condensed in the dry icecondenser and collected. Non-evaporated product mixture (bottom product)and vapor mixture condensed on the internal condenser were removedcontinuously out of the system at a rate equal to the feed rate. Toconduct the run, the heating jacket was heated to 120° C., the reactorpressure was reduced to 11 mm Hg, andS-[3-(triethoxysilyl)propyl]thiooctanoate (10.0 g/min, 27.4 mmol) andsulfuric acid having 2-methyl-1,3-propanol (2.7 g diol/min, 30.0 mmoldiol, 0.003 g/min H₂SO₄) were continuously fed to the system. At the endof one hour, product mixture (719.5 g), vapor mixture (20.0 gr), andethanol lights (60.2 gr) were collected and analyzed. Gas chromatographyanalysis of the product mixture showed 9.7% ethanol, 1.9% unreacted2-methyl-1,3-propanediol, 9.6% unreactedS-[3-(triethoxysilyl)propyl]thiooctanoate, 46.54%3-(1-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate monomer,with the remaining to 100% consisting of related oligomers and siloxanesof 3-(1-methyl-1,3-propanedioxyethoxysilyl)-1-propyl thiooctanoate.

Examples 15, 16 and 17 Preparation of Rubber3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate

In this section, examples are presented that identify the performancedifferences between polysulfide silanes (e.g. TESPD),3-octanoylthio-1-propyltriethoxysilanesilane (OPTES), and the cyclicdialkoxy thiocarboxylate silane,3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate(MPESO) silane.

A typical silica-rubber SBR formulation was used (Table 1). Mixing wascarried out in a 1.6 liter “B” type Banbury with tangential rotors.Silquest®A-1289 (TESPT, bis-(3-triethoxysilyl-1-propyl) tetrasulfide,sold by General Electric Corporation) and Silquest®A-1589 (TESPD,bis-(triethoxysilylpropyl) disulfide, sold by General ElectricCorporation) were chosen as controls. The silane loadings were adjustedto a constant alkoxysilane silicon loading.

TABLE 1 Silica-Silane/Rubber Formulation PHR Ingredient 103.2  SSBR(Buna VSL 5525-1, Bayer AG) 25   BR (Budene 1207, Goodyear) variablesilica (Zeosil 1165MP, Rhodia) variable A-1589 variable3-octanoylthio-1-propyltriethoxysilane-(OPTES) variable3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1- propyl thiooctanoate(MPESO) 5.0 oil (Sundex 8125, Sun Oil) 2.5 zinc oxide (Kadox 720C,ZincCorp.) 1.0 stearic acid (Industrene R, Witco, Crompton) 2.0 6 PPD(Flexzone 7P, Uniroyal, Crompton) 1.5 Wax (Sunproof Improved, Uniroyal,Crompton) Variable Hardness modifiers (carbon-black, fumed silica andaccelerators) Final Mix Ingredients 1.4 Sulfur (#104, Harwick) 1.7 CBSaccelerator (Delac S. Uniroyal, Crompton) 2.0 DPG accelerator (Uniroyal,Crompton)

TABLE 2 Procedure for Two- and One-Non productive mix steps TWO PASSPROCEDURE Step Procedure First Banbury pass: cooling with water @ 25°C., 72% fill factor 1. Add polymers, RDM (ram down mix) 30 seconds @ 117RPM 2. Add 50% silica, all silane, RDM 30 seconds 3. Add remaining 50%silica, oil, RDM 30 seconds 4. Dust down, RDM 20 seconds 5. Dust down,RDM 20 seconds 6. Dust down, RDM @ higher speeds to 160-170° C. (approx.1 minute). Total time for first pass is approx. 5-6 minutes. 7. Dump,sheet off roll mill @ 50-60° C., cool below 60° C. Second Banburypass: 1. Add compound from 1st pass, RDM 30 seconds @ 117 RPM 2. Addremainder of ingredients, RDM 30 seconds 3. Dust down, RDM to 160-170°C. (in approx. 2 minutes) by increasing rotor speed. 4. Hold at 170° C.(or higher temperature) for 8 minutes by changing speeds on mixer. Totaltime for second Banbury pass is approx. 11-12 minutes. 5. Dump, sheetoff roll mill @ 50-60° C. to cool * RDM: Ram down mix time.

Single Pass Procedure

Combine first and second pass of two-pass mix sequence by going to step2 of second pass immediately after completing step 4 of first pass,which eliminates the intermediate cooling step.

Productive Mix

Add sulfur and accelerators (primary and secondary) into the abovemasterbatch on a two-roll mill at 50-60° C. The controls,Silquest®A-1289 (TESPT) and Silquest®A-1589 (TESPD), were mixed in twonon-productive mix steps, which included an intermediate cooling step.The 3-octanoylthio-1-propyltriethoxysilane and MPESO silane-comprisingcompounds were mixed in one non-productive mix step, without anyintermediate cooling step. After all silica, silane and oil areincorporated into the mix, the rpm of the rotors is raised so as toachieve the desired silanization temperature. The mix is then held atthat temperature for 8 minutes. For polysulfide silanes, a cooling stepis needed before this silanization step (sometimes even multiple coolingsteps). 3-Octanoylthio-1-propyltriethoxysilane and MPESO silaneeliminate this need. The mix procedures are shown in Table 2, above.Curing and testing were done according to ASTM standards. In addition,small strain dynamic tests were carried out on a Rheometrics DynamicAnalyzer (ARES—Rheometrics Inc.).

Measurement/Procedure Compound Testing Standards Mooney viscosity andscorch ASTM D1646 Oscillating disc rheometry ASTM D2084 Curing of testplaques ASTM D3182 Stress-strain properties ASTM D412 Heat build-up ASTMD623

Dynamic Mechanical Properties

Payne effect strain sweeps were carried out from dynamic strainamplitudes of 0.01% to about 25% shear strain amplitude at 10 Hz and 60°C. The dynamic parameters, G′_(initial), ΔG′, G″_(max), tan δ_(max) wereextracted from the non-linear responses of the rubber compounds at smallstrains. In some cases, steady state values of tan δ were measured after15 minutes of dynamic oscillations at strain amplitudes of 35% (at 60°C.). Temperature dependence of dynamic properties were also measuredfrom about −80° C. to +80° C. at small strain amplitudes (1 or 2%) at afrequency of 10 Hz.

As observed from Example 15, the OPTES silane compound exhibits lowerMooney viscosity, and decreased non-linearity (lower G′, ΔG′ and tanδ_(max)) compared to TESPD (di-sulfide silane). This is an indication ofimproved silica dispersion and lower hysteresis at 60° C. The OPTESsilane compound also shows superior tensile properties compared to thecontrol TESPD, with a fast rate of growth of its high strain moduli. Thereinforcing index as measured by M300/M100 is higher than TESPD. Thecyclic dialkoxy thiocarboxylate silane (MPESO) was tested at threeloading levels (7.7, 8.2, and 9.0 phr respectively). The compounds usingMPESO show similar processing and performance features as OPTES silanecompound. The overall efficiency of MPESO is slightly inferior thanOPTES silane in these rubber compounds. This can be inferred from thehigher Mooney viscosities and tan δ_(max), hardness and lower moduli andreinforcement indices obtained with compounds using MPESO silane. Theloading level of 8.2 phr for MPESO (at equal rate with OPTES silane) issufficient to maximize all processing and performance attributes of therubber compound. Examples 16 and 17 show simple modifications to themixing procedures and addition of certain ingredients used to improvethe MPESO compound properties up to the levels of OPTES silanecompounds.

Example 16 demonstrates the use of higher mixing times or higher mixingtemperatures (more specifically higher silanization temperatures) toenhance the reaction of MPESO silane with silica—and lead to an overallproperty set closer to OPTES silane compound. From the data, it isclearly evident that, upon increasing the mixing time of MPESO (from 8minutes to 12 minutes) or increasing the mixing temperature from (170°C. to 180° C.), the hysteresis at 60° C. and reinforcing power of MPESOcompounds improve and become essentially equivalent to the compoundsusing OPTES silane.

Another method of improving the processing and performancecharacteristics of MPESO silane was demonstrated in Example 17. In thisexample, certain hydrolysis catalysts that promote the reaction of MPESOwith precipitated silica (viz. diethylene glycol and diethanolamine)were used to enhance the end properties resulting from MPESO rubbercompounds. From the table in Example 17, it was observed that additionof small amounts of DEG or diethanolamine (base catalyst) substantiallyimproved the reinforcing index and moduli growth rate of the MPESOcompounds. The overall processing and performance behavior of MPESOcompounds with DEG or diethanolamine was equivalent to the OPTES silanecompound.

Example 15 Comparison of TESPD, OPTES and MPESO Silane Compounds

MPESO MPESO MPESO TESPD OPTES Lower Loading Equal loading Higher LoadingIngredient (phr) solution SBR 103.2 103.2 103.2 103.2 103.2 Butadienerubber 25.0 25.0 25.0 25.0 25.0 Silica 80 80 80 80 80 TESPD 6.2 OPTES8.2 MPESO 7.7 8.2 9.0 No. of Mixing steps 2 1 1 1 1 Mixing temperature160° C. 170° C. 170° C. 170° C. 170° C. Silanization time (min) 8 8 8 88 Compound properties Processing Mooney Viscosity 72 64 69 69 67 Scorchtime (min) 10.1 11.2 10.5 9.3 8.5 Cure time t90 (min) 14.4 15.0 14.513.2 12.3 M_(L) (dNm) 8.8 7.6 7.9 7.9 7.7 M_(H) (dNm) 27.9 26.2 26.226.4 26.4 Properties in the cured state Non-linearity (0-10%) @ 60° C.G′_(initial) (MPa) 4.47 3.43 3.47 3.15 3.49 ΔG′ (MPa) 2.68 1.82 1.891.77 1.92 G″_(max) (MPa) 0.53 0.37 0.38 0.35 0.37 tanδ_(max) 0.21 0.150.17 0.17 0.16 Wet-Skid Indicator, 10 Hz, 1% DSA tan δ|0° C. 0.400 0.3730.380 0.373 0.391 Reinforcement Hardness (Shore A) 58.0 54.0 55.0 55.056.0 M 25% (MPa) 0.89 0.78 0.84 0.82 0.82 M 100% (MPa) 1.73 1.73 1.731.8 1.78 M 300% (MPa) 8.65 9.55 8.33 8.57 8.54 M 300%/M100% 5.0 5.5 4.84.8 4.8 Elongation at rupture (%) 564.0 530.0 531.0 577.0 581.0 Stressat rupture (MPa) 23.1 23.2 19.9 22.7 22.0

Example 16 Processing and Performance Behavior of MPESO Compounds Mixedat Higher Mixing Times or at Higher Mixing Temperatures

MPESO MPESO TESPD OPTES Higher Mixing time Higher Mixing temp.Ingredient (phr) solution SBR 103.2 103.2 103.2 103.2 Butadiene rubber25.0 25.0 25.0 25.0 Silica 80 80 80 80 TESPD 6.2 OPTES 8.2 MPESO 7.7 8.2No. of Mixing steps 2 1 1 1 Mixing temperature 160° C. 170° C. 170° C.180° C. Silanization time (min) 8 8 12 8 Compound properties ProcessingMooney Viscosity 72 64 65 69 Scorch time (min) 10.1 11.2 10.4 9.1 Curetime t90 (min) 14.4 15.0 13.5 13.3 M_(L) (dNm) 8.8 7.6 7.7 8.0 M_(H)(dNm) 27.9 26.2 25.6 26.0 Properties in the cured state Non-linearity(0-10%) @ 60° C. G′_(initial) (MPa) 4.47 3.43 3.08 3.01 ΔG′ (MPa) 2.681.82 1.49 1.47 G″_(max) (MPa) 0.53 0.37 0.34 0.32 tanδ_(max) 0.21 0.150.15 0.16 Wet-Skid Indicator, 10 Hz, 1% DSA tan δ|0° C. 0.400 0.3730.413 0.410 Reinforcement Hardness (Shore A) 58.0 54.0 54.0 56.0 M 25%(MPa) 0.89 0.78 0.8 0.8 M 100% (MPa) 1.73 1.73 1.74 1.85 M 300% (MPa)8.65 9.55 9.02 9.34 M 300%/M100% 5.0 5.5 5.2 5.0 Elongation at rupture(%) 564.0 530.0 533.0 550.0 Stress at rupture (MPa) 23.1 23.2 21.4 22.1

Example 17 Processing and Performance Behavior of MPESO Compounds UsingDiethylene Glycol

MPESO MPESO TESPD OPTES with glycol with base catalyst Ingredient (phr)solution SBR 103.2 103.2 103.2 103.2 Butadiene rubber 25.0 25.0 25.025.0 Silica 80 80 80 80 TESPD 6.2 OPTES 8.2 MPESO 7.7 8.2 DEG 1.0Diethanolamine 0.5 No. of Mixing steps 2 1 1 1 Mixing temperature 160°C. 170° C. 170° C. 170° C. Silanization time (min) 8 8 8 8 Compoundproperties Processing Mooney Viscosity 72 64 67 66 Scorch time (min)10.1 11.2 9.3 7.0 Cure time t90 (min) 14.4 15.0 12.4 11.5 M_(L) (dNm)8.8 7.6 7.7 8.1 M_(H) (dNm) 27.9 26.2 26.9 26.4 Properties in the curedstate Non-linearity (0-10%) @ 60° C. G′_(initial) (MPa) 4.47 3.43 3.962.84 ΔG′ (MPa) 2.68 1.82 2.20 1.33 G″_(max) (MPa) 0.53 0.37 0.42 0.30tanδ_(max) 0.21 0.15 0.17 0.16 Wet-Skid Indicator, 10 Hz, 1% DSA tanδ|0°C. 0.400 0.373 0.377 0.380 Reinforcement Hardness (Shore A) 58.0 54.057.0 55.0 M 25% (MPa) 0.89 0.78 0.81 0.81 M 100% (MPa) 1.73 1.73 1.831.87 M 300% (MPa) 8.65 9.55 9.25 10.34 M 300%/M100% 5.0 5.5 5.1 5.5Elongation at rupture (% 564.0 530.0 557.0 517.0 Stress at rupture (MPa)23.1 23.2 22.5 23.3

Example 18 VOC Measurements from the Banbury Mixer

The mixing recipe for VOC measurements included all ingredients used inthe non-productive mix steps. Mixing was carried out as indicated inTable 2, until Step 6 of the first non-productive mix step. At thispoint the speed (rpm) of the mixer was raised so as to attain atemperature of 160° C., and the mix was held at that temperature formore than 40 minutes. The mixing times were purposely pushed for longtimes at 160° C. to get the maximum volatile generation possible.

Exhaust vapors were sampled for VOC analysis during compounding in theBanbury mixer. Three silanes, TESPT, OPTES, and MPESO were evaluated. Asampling rate of 320 cc/minute was used. Isopropanol was injected intothe exhaust stream at a given rate to calibrate the experiment, i.e., toestablish an exact known ratio of sampling stream to total exhaust.Exhaust gases were adsorbed on activated charcoal by passing the exhaustsample through a column of the activated charcoal. The charcoal wassubsequently desorbed by saturating the charcoal with carbon disulfide,which quantitatively displaced the adsorbed exhaust gases. Resultsobtained are based on hydrolysis of all alkoxy groups to ethanol.Assumptions were 6 moles of ethanol released per mole of TESPT, 3 forOPTES, and 1 for MPESO. The results obtained from VOC measurements aretabulated below. Based on these results, a substantial reduction in VOCemissions can be achieved by using OPTES and MPESO silanes. Understandard mixing conditions, the MPESO may be expected to provide evenlarger reductions in VOC emissions.

Example 18 VOC Measurements from the Banbury Mixer

EtOH evolved (Kg) Silane phr per Kg of silane Gms. EtOH evolved Loading(Maximum) per Kg of Rubber % VOC reduction Silane Silica: 80 phr Allethoxy's react (Actual) w.r.t. TESPT TESPT 6.2 0.582 13.9 0 OPTES 8.20.379 11.93 14 MPESO 8.2 0.117 5.92 57 OPTES 6.2 0.379 9.02 35 MPESO 6.20.117 4.47 68

Although the invention has been described in its embodiments with acertain degree of particularity, obviously many changes and variationsare possible therein and will be apparent to those skilled in the artafter reading the foregoing description. It is therefore to beunderstood that the present invention may be presented otherwise than asspecifically described herein without departing from the spirit andscope thereof.

Example 19 Preparation of3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate andrelated oligomers from 2-methyl-1,3-propanediol and3-thiooctanoyl-1-propyldiethoxymethylsilane

Into a 100 ml, 3-neck round bottom flask equipped with a magneticstirrer, thermocouple and temperature controller, distillation head andcold finger were charged water (13.55 grams), sodium hydrogen sulfide(45 percent in water, 16.85 grams, 0.1354 moles) and tetrabutylammoniumbromide (50 percent in water, 0.01 grams, 0.015 mmoles). The octanoylchloride (10 grams, 0.0615 moles) was added at room temperature over aperiod of 16 minutes. During the addition, the temperature rose to 38.2°C. The mixture was stirred for an additional 30 minutes and allowed tocool to room temperature. Tetrabutyl ammonium bromide (0.76 grams 0.0185moles) and 3-chloropropylmethyldiethoxysilane (12.95 grams, 0.06154moles) were added and then the mixture was heated at 80° C. for 6 hours.The mixture was cooled to room temperature and the organic phase wasseparated for the aqueous phase using a 250 ml separatory funnel. Theorganic phase was stripped under reduced pressure and nitrogen sparge at140° C. The reaction was repeated to produce more3-thiooctanoyl-1-propyldiethoxymethylsilane. Gas phase analysisindicated that the intermediate was 90.1 percent pure.

Into a 500 ml round bottom flask equipped with a mechanical agitator,condenser (connected to a vacuum pump), dropping funnel, internalthermometer, nitrogen sparge and heating mantle were charged3-thiooctanoyl-1-propyldiethoxymethylsilane (167.3 grams, 0.5 moles) andsulfuric acid (0.106 gram). The mixture was heated to 45° C. underreduced pressure and then the 2-methyl-1,3-propanediol (45.1 grams, 0.5moles) was added dropwise over a 30 minute period. After the additionwas completed, the mixture was stripped under reduce pressure for 30minutes and then the pH of the mixture was adjusted to pH=5.5 usingsodium ethoxide in ethanol (21% sodium ethoxide in ethanol, 0.36 grams).Gas phase analysis of the mixture found 8.3 percent2-methyl-1,3-propanediol, 1.1 percent3-thiooctanoyl-1-propyldiethoxymethylsilane and 53.3 percent3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate. Thebridge diol silane components did not elute from the gas chromatographiccolumn.

Example 20 Preparation of 3-(1,3-Butanedialkoxymethylsilyl)-1-propylthiooctanoate and Related Oligomers from 1,3-butanediol and3-thiooctanoyl-1-propyldiethoxymethylsilane

The 3-(1,3-butanedialkoxymethylsilyl)-1-propyl thiooctanoate wasprepared according to the procedure similar to Example 19, except that1,3-butanediol was substituted for the 2-methyl-1,3-propanediol.

Example 21 Preparation of Rubber Using3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate(MPDMS) and 3-(1,3-butanedialkoxymethylsilane)-1-propyl thiooctanoate(BDMS)

In this section, examples are presented that identify the performancedifferences between bis-(3-triethoxysilylpropyl) disulfide (TESPD),3-thiooctanoyl-1-propyltriethoxysilane (OPTES) and3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate whenused in rubber compounds. A typical silica-rubber SBR formulation givenin Table 1 was used. The silane loadings were adjusted to achieveequivalent silicon loading. The rubber compounds were prepared andtested using according to the procedure similar to the one described inExample 15. The results are present in table below.

Processing and Performance Behavior of3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate(MPDMS) and 3-(1,3-butanedialkoxymethylsilane)-1-propyl thiooctanoate(BDMS)

TESPD OPTES MPDMS BDMS Ingredient (phr) Solution SBR 103.2 103.2 103.2103.2 Butadiene rubber 25 25 75 25 silica 80 80 80 80 TESPD 6.2 OPTES8.2 MPDMS 7.5 BDMS 7.5 No. of mixing steps 2 1 1 1 Mixing temperature160° C. 170° C. 170° C. 170° C. Silanization time (min) 8 8 8 8 CompoundProperties Processing Mooney Viscosity at 71.5 61.6 61.6 63.7 100° C.(ML1 + 4) Scorch at 135° C. 10.2 11.1 10.1 10.3 (MS1 + t₃) (min) Curetime ′t90 (min) 16.2 14.4 11.0 11.3 M_(L) (dN-m) 9.8 7.9 8.4 8.6 M_(H)(dN-m) 30.1 26.9 29.9 30.6 Properties in the cured state Non-linearity(0-10%) 60° C. G′_(initial) (MPa) 4.16 3.12 3.50 3.28 ΔG′ (MPa) 2.571.59 1.81 1.72 G″_(max) (MPa) 0.528 0.414 0.393 0.364 tanδ_(max) 0.1950.156 0.137 0.136 Wet-Skid Indicator, 10 Hz, 1% DSA tanδ 0° C. 0.4220.411 0.481 0.484 Reinforcement Hardness (Shore A) 62 56 60 61 25%Modulus (MPa) 0.939 0.795 0.895 0.914 100% Modulus (MPa) 2.02 1.86 2.372.45 300% Modulus (MPa) 10.81 10.13 12.80 12.72 Reinforcement Index,11.51 12.74 14.30 13.92 (300%/25%) Reinforcement Index, 5.35 5.45 5.405.19 (300%/100%) Elongation at rupture (%) 513 541 501 493 Stress atrupture (MPa) 23.90 23.03 24.17 23.27

1-19. (canceled)
 20. A process for the preparation of a cyclic andbridging dialkoxy silane composition comprising at least one componenthaving a chemical structure selected from the group consisting of:

wherein: each occurrence of the —SiX_(u)Z^(b) _(v)Z^(c) _(w) group isindependently selected from the group consisting of —SiXZ^(c),—SiZ^(b)Z^(c), —SiX₂Z^(b), —SiX₂Z^(b) ₂ and —SiZ^(b) ₃; each occurrenceof R is independently selected from the group consisting of hydrogen,straight, cyclic or branched alkyl group, alkenyl group, aryl group, andaralkyl group, with each R, other than hydrogen, containing from 1 to 18carbon atoms; each occurrence of G is independently selected from thegroup consisting of hydrogen, a monovalent alkyl, alkenyl, aryl oraralkyl group containing from 1 to 30 carbon atoms, and polyvalent groupcontaining from 1 to 30 carbon atoms derived from an alkyl, alkenyl,aryl or aralkyl group; each occurrence of X is independently selectedfrom the group consisting of —Cl, —Br, R¹O—, R¹O(R⁴CR⁵)_(f)O—,R¹C(═O)O—, R¹R²C═NO—, R¹R²NO—, R¹R²N—, —R¹, and—(OSiR¹R²)_(t)(OSiR¹R²R³), wherein each occurrence of R¹, R² and R³ isindependently R; each occurrence of Z^(b), which forms a bridgingstructure between two different silicon atoms, is independently selectedfrom the group consisting of (—O—)_(0.5) and [—O(R⁴CR⁵)_(f)O—]_(0.5),wherein each occurrence of R⁴ and R⁵ is independently R; each occurrenceof Z^(c), which forms a cyclic structure with a single silicon atom, isindependently given by —O(R⁴CR⁵)_(f)O— wherein each occurrence of R⁴ andR⁵ is independently R; each occurrence of the subscripts, u, n, v, w, f,p, r, q, j, p, t, and s, and k, is independently given by u is 0 to 3; nis 1 to 100, with the proviso that when n is greater than 1, v isgreater than 0 and all the valences for Z^(b) have a silicon atom bondedto them; v is 0 to 3; w is 0 to 1 with the proviso that u+v+2w is 3; fis 1 to 15; p is 0 to 5; r is 1 to 3; q is 0 to 6; j is 0 to 1, with theproviso that when j is 0 p is 1; t is 0 to 50; s is 1 to 3; and k is 1and wherein that each of the above structures comprise at least twohydrolysable bridging dialkoxy group, Z^(b), or at least onehydrolysable cyclic dialkoxy group, Z^(c), the process comprisingreacting an aqueous solution of a salt of at least one thioacid with atleast one cyclic and bridging dialkoxy haloalkyl silane and, optionally,at least one haloalkyl silane to provide cyclic and bridging dialkoxysilane composition.
 21. (canceled)
 22. The process of claim 20, whereinthe cyclic and bridging dialkoxy haloalkyl silane is:[L_(r)-G-(SiX_(u)Z^(b) _(v)Z_(w))_(s)]_(n), and the structure for thethiocarboxylate salt is selected from the group consisting of theformula:[(ROC(═O))_(p)-(G)_(j)]-Y¹-SM and(Z^(c) _(w)Z^(b) _(v)X^(u)Si)_(q)-G-Y¹-SM wherein each occurrence of Mis independently selected from alkali metal; ammonium; and mono-, di-,or tri-substituted ammonium; each occurrence of Y¹ is carbonyl; eachoccurrence of R is independently selected from the group consisting ofhydrogen, straight, cyclic or branched alkyl group, alkenyl group, arylgroup, and aralkyl group, with each R, other than hydrogen, containingfrom 1 to 18 carbon atoms; each occurrence of G is independentlyselected from the group consisting of hydrogen, monovalent alkyl,alkenyl, aryl or aralkyl group containing from 1 to 30 carbon atoms, andpolyvalent group containing from 1 to 30 carbon atoms derived fromalkyl, alkenyl, aryl or aralkyl group; each occurrence of X isindependently selected from the group consisting of —Cl, —Br, R¹O—,R¹O(R⁴CR⁵)_(f)O—, R¹C(═O)O—, R¹R²C═NO—, R¹R²NO—, R¹R²N—, —R¹, and—(OSiR¹R²)_(t)(OSiR¹R²R³), wherein each occurrence of R¹, R² and R³ isindependently R; each occurrence of Z^(b), which forms a bridgingstructure between two different silicon atoms, is independently selectedfrom the group consisting of (—O—)_(0.5) and [—O(R⁴CR⁵)_(f)O—]_(0.5),wherein each occurrence of R⁴ and R⁵ is independently R; each occurrenceof Z^(c), which forms a cyclic structure with a single silicon atom, isindependently given by —O(R⁴CR⁵)_(f)O— wherein each occurrence of R⁴ andR⁵ is independently R; each occurrence of L is independently chloro orbromo, and each occurrence of the subscripts, f, j, n, p, q, u, v, w, r,t, and s is independently given by f is 1 to 15; j is 0 to 1, with theproviso that when j is 0 p is 1; n is 1 to 100, with the proviso thatwhen n is greater than 1, v is greater than 0 and all the valences forZ^(b) have a silicon atom bonded to them; p is 0 to 5; q is 0 to 6; u is0 to 3; v is 0 to 3; w is 0 to 1 with the proviso that u+v+2w is 3; r is1 to 3; t is 0 to 50; and s is 1 to 3 and wherein the structure,[L_(r)-G-(SiX_(u)Z^(b) _(v)Z_(w))_(s)]_(n), comprises at least twohydrolysable bridging dialkoxy groups, Z^(b), or at least onehydrolysable cyclic dialkoxy group, Z^(c).
 23. (canceled)
 24. (canceled)25. The process of claim 20, wherein the reaction temperature is about40 to about 85° C. and the pressure is ambient.
 26. The process of claim20, wherein the reaction is carried out in the presence of at least onephase transfer catalyst of the formula:(R⁶R⁷R⁸R⁹N⁺)_(m)A^(−m) wherein each occurrence of R⁶, R⁷, R⁸ and R⁹ isindependently R, where R is selected from the group consisting ofhydrogen, straight, cyclic or branched alkyl group-alkenyl group, arylgroup, and aralkyl group, with each R, other than hydrogen, containingfrom 1 to 18 carbon atoms; N is nitrogen; A^(−m) is a monovalent orpolyvalent anion selected from the group consisting of fluoride,chloride, bromide, iodide, sulfate, bisulfate, carbonate, bicarbonate,hydroxide, phosphate, carboxylate, thiocarboxylate, sulfide, andhydrosulfide, where the minus sign denotes that the species is an anion,and m denotes the number of negative charges on the anion; and thesubscript m is a positive integer of from 1 to
 6. 27. (canceled) 28.(canceled)
 29. The process of claim 26, wherein the phase transfercatalyst is selected from the group consisting of tetramethylammoniumchloride, tetramethylammonium bromide, tetramethylammonium iodide,tetramethylammonium hydroxide, tetraethylammonium chloride,tetraethylammonium bromide, tetraethylammonium iodide,tetraethylammonium hydroxide, tetrabutylammonium chloride,tetrabutylammonium bromide, tetrabutylammonium iodide,tetrabutylammonium hydroxide, methyltributylammonium chloride,methyltributylammonium bromide, methyltributylammonium iodide,methyltributylammonium hydroxide, tetraoctylammonium chloride,tetraoctylammonium bromide, tetraoctylammonium iodide,tetraoctylammonium hydroxide, methyltrioctylammonium chloride,methyltrioctylammonium bromide, methyltrioctylammonium iodide,methyltrioctylammonium hydroxide, benzyltrimethylammonium chloride,benzyltrimethylammonium bromide, benzyltriethylammonium chloride,benzyltributylammonium chloride, dibenzyldimethylammonium chloride,dibenzyldimethylammonium bromide, dibenzyldiethylammonium chloride anddibenzyldibutylammonium chloride.
 30. A process for the preparation of acyclic and bridging dialkoxy silane composition comprising at least onecomponent having a chemical structure selected from the group consistingof:

wherein: each occurrence of the —SiX_(u)Z^(b) _(v)Z^(c) _(w) group isindependently selected from the group consisting of —SiXZ^(c),—SiZ^(b)Z^(c), —SiX₂Z^(b), —SiXZ^(b) ₂ and —SiZ^(b) ₃; each occurrenceof R is independently selected from the group consisting of hydrogen,straight, cyclic or branched alkyl group, alkenyl group, aryl group, andaralkyl group, with each R, other than hydrogen, containing from 1 to 18carbon atoms; each occurrence of G is independently selected from thegroup consisting of hydrogen, a monovalent alkyl, alkenyl, aryl oraralkyl group containing from 1 to 30 carbon atoms, and a polyvalentgroup containing from 1 to 30 carbon atoms derived from alkyl, alkenyl,aryl or aralkyl group; each occurrence of X is independently selectedfrom the group consisting of —Cl, —Br, R¹O—, R¹O(R⁴CR⁵)_(f)O—,R¹C(═O)O—, R¹R²C═NO—, R¹R²NO—, R¹R²N—, —R¹, and—(OSiR¹R²)_(t)(OSiR¹R²R³), wherein each occurrence of R¹, R² and R³ isindependently R; each occurrence of Z^(b), which forms a bridgingstructure between two different silicon atoms, is independently selectedfrom the group consisting of (—O—)_(0.5) and [—O(R⁴CR⁵)_(f)O—]_(0.5),wherein each occurrence of R⁴ and R⁵ is independently R; each occurrenceof Z^(c), which forms a cyclic structure with a single silicon atom, isindependently given by —O(R⁴CR⁵)_(f)O— wherein each occurrence of R⁴ andR⁵ is independently R; each occurrence of the subscripts, u, n, v, w, f,p, r, q, j, p, t, and s, and k, is independently given by u is 0 to 3; nis 1 to 100, with the proviso that when n is greater than 1, v isgreater than 0 and all the valences for Z^(b) have a silicon atom bondedto them; v is 0 to 3; w is 0 to 1 with the proviso that u+v+2w is 3; fis 1 to 15; p is 0 to 5; r is 1 to 3; q is 0 to 6; j is 0 to 1, with theproviso that when j is 0 p is 1; t is 0 to 50; s is 1 to 3; and k is 1and wherein that each of the above structures comprise at least twohydrolysable bridging dialkoxy group, Z^(b), or at least onehydrolysable cyclic dialkoxy group, Z^(c), the process comprisingreacting a thiocarboxylate-alkoxy silane having an alkoxysilyl moietywith a diol of the general formula:HO(R⁴CR⁵)_(f)OH in the presence of a catalyst to effect thetransesterification of the alkoxysilyl moiety of thethiocarboxylate-alkoxy silane and provide the cyclic and bridgingdialkoxy silane composition.
 31. (canceled)
 32. The process of claim 30carried out in the presence of a catalyst which is an acid, base ortransition metal-containing compound.
 33. The process of claim 32, wherethe acid is selected from the group consisting of p-toluenesulfonicacid, sulfuric acid, hydrochloric acid, chlorosilanes, chloroaceticacid, phosphoric acid and mixtures thereof; the base is selected fromthe group consisting of sodium methoxide, sodium ethoxide and mixturesthereof; the transition metal-containing compound is selected from thegroup consisting of tetraisopropyl titanate, dibutyltin dilaurate,titanium alkoxides, titanium-containing chelates, zirconium alkoxides,zirconium-containing chelates and mixtures thereof.
 34. The process ofclaim 30, wherein the catalyzed reaction of silane and diol is carriedunder distillation to remove volatile alcohol by-product.
 35. (canceled)36. The process of claim 30, wherein the diol is selected from the groupconsisting of 1,2-ethylene glycol, neopentyl glycol, 1,2-propanediol,1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol,2-methyl-2,4-pentanediol, 1,4-butanediol, 1,6-hexanediol, cyclohexanedimethanol, pinacol and mixtures thereof.
 37. (canceled)
 38. The processof claim 30, where the reaction temperature is about 30 to about 90° C.39. (canceled)
 40. The process of claim 30, where the reaction pressureis about 1 to about 80 mm Hg absolute pressure.
 41. The process of claim30, wherein a molar ratio of at least about 0.5 moles of diol peralkoxy-silyl in the silane is employed.
 42. (canceled)
 43. (canceled)44. The process of claim 30, further comprising: a) reacting, in a thinfilm reactor, a thin film reaction medium comprising athiocarboxylate-alkoxy silane, a diol and a catalyst to provide adiol-derived thiocarboxylate-alkoxy silane and a by-product alcohol; b)vaporizing the by-product alcohol from the film to drive the reaction;c) recovering the diol-derived thiocarboxylate-alkoxy silane reactionproduct; d) optionally, recovering the by-product alcohol bycondensation; and, e) optionally, neutralizing the diol-derivedthiocarboxylate-alkoxy silane product to improve its storage stability.45. The process of claim 44, where the film is formed in a falling filmevaporator device, a wiped film evaporator device or a distillationcolumn. 46-56. (canceled)
 57. A process for preparing a cured rubbercomposition comprising: (a) thermomechanically mixing, in at least onepreparatory mixing step, under effective mixing conditions, at least onerubber composition according to claim 48; (b) subsequently blendingtherewith, in a final thermomechanical mixing step under effectiveblending conditions, at least one deblocking agent and optionally atleast one curing agent; and, optionally, c) curing the mixture undereffective curing conditions to provide a cured rubber composition.
 58. Atire at least one component of which comprises the cured rubbercomposition obtained from the rubber composition of claim
 48. 59.(canceled)
 60. A free flowing filler composition comprising at least onesilane and a particulate filler, the silane having a chemical structureselected from the group consisting of:

wherein: each occurrence of the —SiX_(u)Z^(b) _(v)Z^(c) _(w) group isindependently selected from the group consisting of —SiXZ^(c),—SiZ^(b)Z^(c), —SiX₂Z^(b), —SiXZ^(b) ₂ and —SiZ^(b) ₃; each occurrenceof R is independently selected from the group consisting of hydrogen,straight, cyclic or branched alkyl group, alkenyl group, aryl group, andaralkyl group, with each R, other than hydrogen, containing from 1 to 18carbon atoms; each occurrence of G is independently selected from thegroup consisting of hydrogen, a monovalent alkyl, alkenyl, aryl oraralkyl group containing from 1 to 30 carbon atoms, and a polyvalentgroup containing from 1 to 30 carbon atoms derived from alkyl, alkenyl,aryl or aralkyl group; each occurrence of X is independently selectedfrom the group consisting of —Cl, —Br, R¹O—, R¹O(R⁴CR⁵)_(f)O—,R¹C(═O)O—, R¹R²C═NO—, R¹R²NO—, R¹R²N—, —R¹, and—(OSiR¹R²)_(t)(OSiR¹R²R³), wherein each occurrence of R¹, R² and R³ isindependently R; each occurrence of Z^(b), which forms a bridgingstructure between two different silicon atoms, is independently selectedfrom the group consisting of (—O—)_(0.5) and [—O(R⁴CR⁵)_(f)O—]_(0.5),wherein each occurrence of R⁴ and R⁵ is independently R; each occurrenceof Z^(c), which forms a cyclic structure with a single silicon atom, isindependently given by —O(R⁴CR⁵)_(f)O— wherein each occurrence of R⁴ andR⁵ is independently R; each occurrence of the subscripts, u, n, v, w, f,p, r, q, j, p, t, and s, and k, is independently given by u is 0 to 3; nis 1 to 100, with the proviso that when n is greater than 1, v isgreater than 0 and all the valences for Z^(b) have a silicon atom bondedto them; v is 0 to 3; w is 0 to 1 with the proviso that u+v+2w is 3; fis 1 to 15; p is 0 to 5; r is 1 to 3; q is 0 to 6; j is 0 to 1, with theproviso that when j is 0 p is 1; t is 0 to 50; s is 1 to 3; and k is 1and wherein that each of the above structures comprise at least twohydrolysable bridging dialkoxy group, Z^(b), or at least onehydrolysable cyclic dialkoxy group, Z^(c).
 61. The free flowing fillercomposition of claim 60, wherein the silane is selected from the groupconsisting of 2-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-ethylthioacetate; 2-(2-methyl-2,4-pentanedialkoxymethoxysilyl)-1-ethylthioacetate; 2-(2-methyl-2,4-pentanedialkoxy methylsilyl)-1-ethylthioacetate; 3-(2-methyl-2,4-pentanedialkoxymethoxysilyl)-1-propylthioacetate; 2-methyl-2,4-pentanedialkoxyethoxysilylmethyl thioacetate;2-methyl-2,4-pentanedialkoxyisopropoxysilylmethyl thioacetate;neopentylglycoxypropoxysilylmethyl thioacetate;propyleneglycoxymethylsilylmethyl thioacetate;neopentylglycoxyethylsilylmethyl thioacetate;2-(neopentylglycoxyisopropoxysilyl)-1-ethyl thioacetate;2-(neopentylglycoxy methylsilyl)-1-ethyl thioacetate;2-(1,3-butanedialkoxymethylsilyl)-1-ethyl thioacetate;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl thioacetate;3-(1,3-butanedialkoxyisopropoxysilyl)-4-butyl thioacetate;3-(1,3-butanedialkoxyethylsilyl)-1-propyl thioacetate;3-(1,3-butanedialkoxymethylsilyl)-1-propyl thioacetate;6-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-hexyl thioacetate;1-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-5-hexyl thioacetate;8-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-octyl thioacetate;10-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-decyl thioacetate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiododecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-methylheptanoate; 6-(1,3-butanedialkoxyethoxysilyl)-1-hexylthioacetate; 1-(1,3-butanedialkoxyethoxysilyl)-5-hexyl thioacetate;8-(1,3-butanedialkoxyethoxysilyl)-1-octyl thioacetate;10-(1,3-butanedialkoxyethoxysilyl)-1-decyl thioacetate;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(1,3-butanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(1,3-butanedialkoxypropoxysilyl)-1-propyl thiododecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-methylheptanoate;3-(2-methyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-propanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiodecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiododecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiotetradecanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propylthio-2-methylheptanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxyethoxysilyl)-1-propyl thiodecanoate; and3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl thioacetate;2-methyl-2,4-pentanedialkoxyisopropylsilylmethyl thioacetate;6-(2-methyl-2,4-pentanedialkoxyethylsilyl)-1-hexyl thioacetate;1-(2-methyl-2,4-pentanedialkoxymethylsilyl)-5-hexyl thioacetate;8-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-octyl thioacetate;10-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-decyl thioacetate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl thiodecanoate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propyl thiododecanoate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthio-2-ethylhexanoate;3-(2-methyl-2,4-pentanedialkoxymethylsilyl)-1-propylthio-2-methylheptanoate; 3-(1,3-butanedialkoxybutylsilyl)-4-propylthioacetate; 3-(1,3-butanedialkoxyisopropylsilyl)-4-butyl thioacetate;6-(1,3-butanedialkoxymethylsilyl)-1-hexyl thioacetate;8-(1,3-butanedialkoxymethylsilyl)-1-octyl thioacetate;1-(1,3-butanedialkoxymethylsilyl)-1-decyl thioacetate;3-(1,3-butanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(1,3-butanedialkoxymethylsilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-butanedialkoxypropylsilyl)-1-propyl thiododecanoate;3-(2,2-dimethyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiodecanoate;3-(2,2-dimethyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thiooctanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propyl thiodecanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propyl thiododecanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propylthiotetradecanoate; 3-(2-methyl-1,3-propanedialkoxymethylsilyl)-1-propyl thio-2-ethylhexanoate;3-(2-methyl-1,3-propane dialkoxymethylsilyl)-1-propylthio-2-methylheptanoate; and neopentylglycoxypropylsilylmethylthioacetate.
 62. The free flowing filler composition of claim 60 whereinthe filler is chemically inert relative to the silane.
 63. (canceled)64. The free flowing filler composition of claim 60 wherein the filleris a siliceous material.